Yellow Stainer Mushroom

Horse & Field Mushroom Imposter! – The Yellow Stainer

It’s a Sunday afternoon and I pass by a grass verge near my house. My heart jumps at the sight of a huge cluster of (what seem to be) Horse mushrooms or possibly Field mushrooms, but this is no field, just a grassy verge near trees at the side of the road! I was without a basket or bag so like a kid in a sweet shop I scooped up a good share, leaving some to drop their spores.

But my dreams of a nice fry up or even a creamy mushroom soup are soon quaffed because I suddenly realise these mushrooms are not what they appear to be. I wait until I get home around the corner to double check. Read on…

Image of yellow marking on Agaricus xanthodermus

Chrome yellow staining on cap edge. Bulbous base.

I’m not surprised at all that the Yellow Stainer (Agaricus xanthodermus) is responsible for the most cases of mushroom poisoning in this country. Although this evil twin of our favourite field, wood and Horse mushrooms is not deadly it can keep you in the loo for longer than you normally do! Gastric symptoms can persist for up to 24 hours. Fortunately I have not been caught out yet, but some people after consumption usually get away with only mild upset or sometimes have no reaction at all. My Uncle once told me “Ooh, I don’t get along with those Yellow Stainers – don’t like ’em” . Let’s hope that it was only his palette they offended – I didn’t ask!

So how on earth can I identify this poisonous peril when compared to a Horse mushroom? I hear you all cry!

Don’t rely on the ‘overall look’. They differ in colour from pure white to brown/grey, scaly and smooth, tall and short and so on. Horse mushrooms can display some paler yellow on the cap and stem – so if you do see some yellow it’s not always a bad thing.

Both the Horse Mushroom and Yellow Stainer ‘bruise’ yellow (There’s hardly any yellow about the Field mushroom). But the Yellow Stainer has a stronger chromium yellow once bruised. If you rub the cap with your thumb, there will be a very noticeable colour change. But the crunch test for me is at the very base. Take a knife to the very bottom of the stem (the base is more bulbous than the others) and cut in half (see picture below). If the colour changes to a vivid yellow, then you’ve got yourself a Yellow Stainer. Horse and Field mushrooms do not stain at the base like this.

Other good ID tips are:
1. The smell is an unpleasant (phenol/inky smell more apparent when being cooked)
2. The ring on the stem is large and floppy.
3. Before the veil drops it does not have the ‘cogwheel’ pattern like the Horse Mushroom.
4. Gills when very young are white unlike the Horse and Field mushrooms which are pink

In addition to point 3 – if you’re new to collecting mushrooms, avoid very young specimens as they also can be confused with much more poisonous (even deadly) young toadstools.

The Yellow Stainer - Poisonous UK mushroom

Horse and Field Mushroom lookalike – The Yellow Stainer. Notice the chrome yellow colouring at the base of a cut stem.

Large ring of Yellow Stainer mushroom

On open caps: The ring on the Yellow Stainer is noticably large and floppy. The Field Mushroom’s ring is a fine torn frill. The Horse Mushroom’s ring is formed of a double membrane. The lower part is ‘star shaped’

Quick ID checlist for Agaricus Xanthodermus.

The Genus AGARICUS (Wood Mushrooms/Mushrooms): Characteristics to look out for:

• Many discolour yellowish, reddish or pinkish when cut or bruised.
• Those that discolour bright/chrome yellow should be avoided for consumption.
• Gills in young specimens are often pink (white in a few) – maturing darker brown.
• Make note of any smells, such as aniseed or a typical strong ‘supermarket’ mushroom smell.

115 replies
  1. Maggie
    Maggie says:

    Yes – these little blighters are so similar – we ate them by accident last night, but I’m relieved to say that we had no adverse effects from them. If you find that they turn a real yellow when cooking, then discard them immediately!

    Reply
      • David
        David says:

        They taste pretty strong, actually after a few you don’t want any more lol
        I have no adverse affects, must be my strong immune system (I am 66) but I gave some to my neighbors and my son’s mother, she put one in the microwave and it turned yellow so she didn’t eat them (but never told me haha) I cooked mine with other food so didn’t notice. I’ve eaten over a dozen of these with no effects, but this time I bruised some of them and noticed the yellow – checked online and here I am :D

        Reply
        • J C Harris
          J C Harris says:

          My uncle is just the same. I think he just eats them and says he doesn’t like them very much. Again, no ill effects! Which is fortunate I guess :)

          Reply
    • Andy
      Andy says:

      I noticed they turned yellow when cooking and read your article. I discarded the mushrooms. Great advice thank you so much

      Reply
    • Ben Sowton
      Ben Sowton says:

      Thanks very much for that as I cooked mine and they went very yellow. I had no idea about the Yellow Stainer so I really appreciate the blog and your input

      Reply
    • Ralph Hardie
      Ralph Hardie says:

      Just what i was going to say …yellow when frying…
      I’ve actually eaten them before years ago and wasn’t well for a day… not nice…

      Reply
  2. Al Reid
    Al Reid says:

    The inky (phenol) taste is unmistakable (although the regular mushroom taste is still there underneath). On cooking the phenol smell becomes stronger and they do become very yellow.
    I nibbled a raw one experimentally as I was so certain it was a horse mushroom. i didn’t suffer any ill effects – either because I’m immune (some are) but more likely because I didn’t eat enough.

    Reply
    • J C Harris
      J C Harris says:

      Good point on the smell. I have not been on the receiving end of the cooked smell since I have not cooked any. Phenol is the predominant chemical in these mushrooms along with a few other nasty chemicals, but not in volume that are life threatening. Thanks for the comment. It’s good to know in case anyone gets to the cooking stage – it’ll be a last warning!

      Reply
  3. suedobie
    suedobie says:

    I picked over 1 kilo of what I thought were Horse Mushrooms on a walk last Friday and had plans to make some delish soup when I got home, I know Horse Mushrooms stain yellow but decided to check in my Mushroom Book by Roger Phillips, having a small doubt in my mind I started searching on the net and found your site.

    Unfortunately I have a habit of breaking of the stem half way down a throwing the dirty bit away so that the rest of my “Booty” does not get soil on, so having read your list of things to look for to tell the difference between Horse and Yellow I did not have a vital piece that I needed.

    I had picked some not very far from where I live so off I went to get a couple more, when I cut the whole of the stem in half it went yellow at the very bottom, feeling disappointed I threw the lot in the bin.

    Last week I ate some that I had cooked, they did go very yellow but I assumed that was because I cooked them in butter, although they did not taste great they did not taste very unpleasant either, thankfully I too did not suffer any adverse effects.

    Is it my imagination or does there seem to be lots of Yellow Stainers about at the moment?

    Reply
    • J C Harris
      J C Harris says:

      I understand what you’re saying. I myself piled in to a massive stock of what I thought were field or horse mushrooms! I even have a photo of myself with the catch. But now I’m too embarrassed to show it after realising the true nature of my discovery! It’s always best to get the ‘whole’ of the mushroom, base and all, to help in identification. I know how easy it is to get carried away in picking mushrooms.

      It’s true though! The ratio in my Yellow stainer/Horse or field mushroom discoveries is 3:1

      It’s also interesting to note that 2010 so far has been an exceptionally good year for mushrooms – we’re going to get loads of different species at all times. The desirable are going to be as common as the undesirable.

      Reply
  4. R F Parker
    R F Parker says:

    Picked some mushrooms that I was fairly sure were horse mushrooms this p.m. The location was on a scarp slope of kentish chalk downland. I have gathered genuine horse mushrooms from a location within a few hundred metres of this site (but under some hawthorn trees, unlike these which were in open field/grazing pasture) in the past and enjoyed their delicious flavour so was pretty sure that these would be the same species. However, it is late in the season and it has been cold and fairly dry so these examples were immature and small. Nearby were some that had rotted and were maggotty and they certainly looked like horse mushrooms. However, although to me they smelt good enough, my specimens went a bright yellow when cooked (I don’t remember this with my previous encounters with horse mushrooms). I am still not entirely sure which species I found because they were so small – gills were a pale beige/pink and the cap was white with a beige tinge on the slightly larger specimens. I decided to discard them to be on the safe side.

    Reply
    • J C Harris
      J C Harris says:

      I sympathise with your frustration. Sometimes Yellow Stainers don’t smell that bad to me although not holding that strong, typical mushroom smell. There are many Agaricus species out there, obviously some more common than others, but even a few days ago I found an extremely uncommon species just down the road on a grass verge, looking like smaller versions of Horse mushrooms with a few extra characteristics!

      If the mushrooms you found were very young and had pale beige/pink then that confuses things more! Young Yellow Stainers have white gills when young or even pale-pale beige. So they could’ve been Yellow Stainers.

      Some Agaricus species have white gills when young and some others, pinkish! And because people don’t report on changes in colour, smell etc. whilst cooking every mushroom (like you good people out there) there is no reliable record of what species you’ve actually got.

      If it’s not too late, you could go back to the place you found them and see what they’re like when matured. I sometimes do this and it really helps in identification.

      Reply
  5. jayne
    jayne says:

    hi, i picked what i thought were field mushrooms yesterday ( nov 25th ) late for mushrooms i know but thought i’d stumbled on a bounty! my husband was looking forward to them with his steak supper. when i picked them they turned yellow ( i dont know anything about mushrooms so thought this was normal) but when i got home the yellow had gone. upon cooking they went very yellow and the smell was very bad. my husband ate one and decided to leave the rest as the taste was “chemical” in his words. luckily he hasnt suffered any bad reaction. lesson learned!!

    Reply
  6. J C Harris
    J C Harris says:

    Glad to hear your husband didn’t suffer any ill effects. The mushroom season has been a little late to reach full bloom, due to the dry weather earlier in the year. November has been a good month for mushrooms this year. Even today (Nov 27th) I found a large group of Yellow stainers again myself.

    Reply
  7. bev
    bev says:

    Hi. I have just picked some mushrooms. The base stains yellow when cut but the gills are pink and they don’t seem to smell. I’m going to err on the side of caution but wondered if toy had any idea whether the are likely to be yellow stainers. Thanks.

    Reply
    • J C Harris
      J C Harris says:

      Hi Bev

      Don’t worry about the ‘old post’ thing. People still visit this story. It’s my most popular post.
      Anyway, sounds very much like a yellow stainer so avoid. Try rubbing the cap near the edge and wait to see if turns chrome yellow also.
      All the best
      John

      Reply
  8. Ken Fox
    Ken Fox says:

    I picked some of these today but realised they weren’t field mushrooms because of the smell. Reminded me of the calamine lotion that my mum used to put on my skin as sun protection, but they do also smell of ink. Didn’t notice the yellow stains when I picked, but they went yellow when I fried them. Ate one bit but decided against serving them up to family and friends. Just as well. Slight stomach cramps but nothing serious.

    Reply
    • J C Harris
      J C Harris says:

      Lucky you tried a little first Ken before serving. As mentioned before, the cooking of them is the last warning. I agree with you on the inky smell too, it is not that nice really.

      Reply
  9. Mark Hadley
    Mark Hadley says:

    I’m glad I saw this site, albeit too late! I picked a massive 3Kgs of what i thought were the usual field mushrooms, dishing out the bigger open ones to my parents for an early foraged breakfast and keeping the smaller closed cups for my own breakfast.
    Maybe because it was early in the morning, I wasn’t put off by the chromium yellow colour they went when cooked, because you sometimes get a yellowish tinge when cooking horse mushrooms, I piled through them, only for them to return with a vengeance 3hrs later.
    TIP: Don’t try and eat half a Kg of these on your own, or your senses are dulled from last nights bottle of claret.
    Now I’ve read the comments I can see that the most recognisable difference was the very thin floppy annulus, which should have told me that these were slightly different, I like others didn’t see the yellow in the base as I cut off above this to leave the mycelium intact.
    Well you learn something new everyday, I’ve been eating wild foraged fungi for years and never got caught out before. Little yellow blighters!

    Reply
    • J C Harris
      J C Harris says:

      They are blighters indeed. They even had me fooled once again this week. After a couple of checks I knew instantly they were Yellow Stainers. Boo! When we’re picking wild mushrooms like this (when we think they’re something else) most of us do cut above the base of the stem, so a test at home to see the yellow isn’t possible. And you’re right about the larger floppy ring. That is a good characteristic. My other useful ‘never fails’ test is to slightly vigorously rub the side of the cap – the chrome yellow colour shows up very fast as a good warning sign.

      Anyway, I hope you didn’t suffer too much Mark and I hope your better now.

      All the best
      John

      Reply
  10. Rachel
    Rachel says:

    John, what a lovely site and a very helpful post and comments to help with the horse/field/yellow stainer dilemma. I have found a patch of neglected horse mushrooms near an occasional car park and wondered if it were worthwhile trying to transplant some to a safer site. Do you have any views or advice?

    Reply
    • J C Harris
      J C Harris says:

      Thank you for the feedback Rachel. Always good to hear happy/positive feedback. It makes my ‘labour of love’ blogging feel worthwhile. Regarding your question about moving Horse mushrooms to your patch is very interesting, and has always interested me. A lot of favourable mushrooms are extremely hard if not impossible to harvest on a commercial level with the obvious exception of Oyster and our well known Supermarket mushrooms (Agaricus bisporus) plus a few more. But I did move a small collection of young to mature field mushrooms onto my lawn (keeping them well away from any trees, cap naturally gills down). The next year I had a harvest of one!! but I didn’t expect them to take at all, it was a nice surprise. It’s not something I have tried since because I love the getting out and foraging side so much. But I think it’s worth a go, especially with Agaricus (mushroom) species. If you have, or know of a place with good conditions you can easily access locally (so you get first grabs!) then placing a few caps there might turn into something good. I could be talking nonsense but it has worked for me on a small scale, even though they haven’t fruited this year. Maybe a lost cause, I don’t know. But if you do try it, let me know the results next year (or the year after)!

      All the best
      John

      Reply
      • Bev Lane
        Bev Lane says:

        I have had some success with transferring mature caps of pine mushrooms (Lactarius deliciosus) and several Boletus species to my garden. Lay them spore side down near the drip line of a coniferous tree, so their mycelium can penetrate the young root tips. Both groups of fungi are symbionts, not parasites, which is to say that they have a cooperative mycorrhizal relationship with the host tree, helping it to absorb more water and nutrients from the soil in exchange for sugars which the tree generates by photosynthesis. Both kinds took a couple of years to produce caps.

        Reply
  11. Luan Schoeman
    Luan Schoeman says:

    So I found a bounty too! Large (up to 19 cm caps) about 1 kg in total, dark chocolate brown gills, thin ring (not really skirt like) no yellow stain in the stipe base at all, smell strongly like mushroom and I cant really say they smell ‘inky’… but the young caps stain slightly yellow (definitely yellow) when bruised. Now I’m paranoid!!! I want to have them for dinner! Thought they were horse mushrooms! ??

    Reply
    • J C Harris
      J C Harris says:

      They could be horse mushrooms, which can stain yellow. The Yellow Stainer stains more ‘chrome’ yellow which is VERY yellow. Cook a couple to test. If you’ve got the Y.S. the unpleasant smell will be more apparent and they will turn yellow even further. If in doubt though – do without!

      Reply
      • Luan Schoeman
        Luan Schoeman says:

        So I asked advice from some people who knew the mushrooms of the area. They were definitely Agaricus, but not Xanthodermus. Probably Campestris. I cooked a little one, smelled it, inspected the colour and ate it. Tasted great. Ate the entire lot in a soup the next day. Cant wait for my next find!!!
        Conclusion: South Africa (Cape region) hosts some Agaricus species that yellows in the cap when bruised, but not in the stipe and not extremely yellow.

        Reply
  12. aidee
    aidee says:

    Mushrooms have popped up in the backyard after autumnal rains here in Oz, with a google search re yellow bruising leading here. Thanks therefore for the great mushroom resource and for saving me an arvo on the loo :)

    Reply
  13. Carol
    Carol says:

    I have found heaps on these mushrooms on our property in South Australia (Mt Compass area) especially this winter, and I have previously cooked and eaten these with no ill effects. But the taste and smell when cooked is not very appetising. I thought the yellow colour might be caused from a high iodine content but they did have a strong chemical taste.

    Reply
  14. there's old shroomer''s n bold shroomer's but no old bold shroomer's
    there's old shroomer''s n bold shroomer's but no old bold shroomer's says:

    I picked a plump white capped, pink gilled, thick stemmed shroom in the middle of a field I have had many shrooms from. On prepping it, as I snapped the bottom of the stem it turned pink. I’ve looked online to no avail. Can you help please?

    Reply
  15. Hannele Weir
    Hannele Weir says:

    Thanks to this site and numerous examples of ‘Yellow Stainers” , I ran a test, cooking small batches of the mushrooms I picked yesterday. The ones I was suspicious of, did indeed turn yellow on cooking, and so were discarded.
    What initially made me suspicious of them was that their stems were rather hollow, and that there was some yellow staining at the base when I picked them. However, I did not detect any characteristic smell either raw or when I test cooked them, but they turned bright yellow. Thank you for the very helpful advice in identifying the Yellow Stainers.

    Hanna

    Reply
    • J C Harris
      J C Harris says:

      Hi Hannele. It always good to run the ‘cooking test’ thanks to other peoples experiences and advice. I never trust bright yellow staining at the base of the stem and I understand about the smell. Sometimes I can’t often detect much of an odour. I think this varies from mushroom to mushroom, I rely much more on the visual characteristics. I have never cooked any so I can’t advise on the reliability of smell during cooking. It’s a good ‘alarm call’ that they turn bright yellow in the pan…

      All the best
      John

      Reply
  16. Sylvia Mathews
    Sylvia Mathews says:

    Dear John – I am 78 yrs old and living here in Houston, Texas.

    I was searching to identify some really huge mushrooms that grow in the fall usually in the medians of the streets which probably is rich with the mushroom spores. They are big 6″to 10″ caps and color of toasted bread usually grow in the fall

    I could not find any info on them. Anyway I began reading your interesting site and enjoyed it so much. However, I became so hungry for mushrooms I am going out at 9:45 pm to supermarket for some right now // I Love oyster mushrooms but only ever had them canned. I am from deep South Louisiana and had some red squirrels my dad gave me and I seasoned with our good old Cajun seasoning marinating a couple hours, drained them and browned nicely in a little oil, threw in a couple of finely sliced yellow onions, a medium sized green bell pepper sliced nicely, added 1 cup water, put a good tight lid on the pot turned the flame down to simmer until meat was ready to fall off the bone, added a couple cans of the drained oyster mushrooms and served it on nice hot fluffy medium grain rice {not that precooked junk} and bingo I am now sitting here all alone enjoying my squirrel with the rich brown gravy and nice large pieces of the oyster mushroom. Please let me know if you find out if those giant mushrooms are edible or what. Nice meeting you and all your followers.

    Sylvia from Houston, Texas

    Reply
    • J C Harris
      J C Harris says:

      Thanks for the feedback Sylvia and for your recipe. Mind you, Red Squirell’s are rare here and protected by law, so us UK guys would have to choose something else! But the big mushrooms you talk of are maybe an Agaricus species, and maybe the ‘Agaricus macrosporus’ mushroom which is similar to the Horse Mushroom (see my post here: https://www.mushroomdiary.co.uk/2013/09/horse-mushrooms-identification-agaricus-arvensis). Its cap can grow very large indeed, up to 25cm. But if they pop up again, check with a local expert if you can to make sure they’re safe to eat. I’m not 100% sure of all species in Louisiana. Anyway. I hope you enjoyed your meal and glad you are enjoying my blog.

      All the best
      John

      Reply
    • J C Harris
      J C Harris says:

      It is a bright vivid yellow. See the picture of the base of the stem cut in half. The edge of the cap will turn this yellow colour too. Sometimes two Yellow Stainers will grow side by side and their caps rub against each other as they grow, leaving a strong bright yellow stain. Horse and Field mushrooms, along with the many of the Agaricus species do not have such strong yellow discolouring. The strong yellow is also very contrasty against the whitish cap. Hope that helps.

      All the best
      John

      Reply
  17. Michelle
    Michelle says:

    Thank you so much for your photos of Yellow Stainers! I was just about to fry up what I thought was a delicious crop of Field Mushrooms gathered from a grass verge at the end of my road, but thought I would double-check when I noticed the yellow tinge on the stem. Saved from a day in the loo….

    Reply
  18. Peter
    Peter says:

    I have noticed these mushrooms can be quite variable in look and the yellow staining can take some time to appear. I agree the smell is the biggest decider if it ‘passed’ the other checks ..edible mushrooms should smell delicious but these have a sort of antiseptic smell to my nose. They seem associated with ash tree roots where I live. (anecdotal digging) My neighbour ate them with no ill effects but I binned mine and I am now extra careful. Now, picking a bunch of aconite led to some interesting symptoms to be avoided!
    Thank you for your informative website.

    Reply
  19. Chris
    Chris says:

    I found 5 normal mushrooms, they were not under a tree, i ate them 5 days ago they were good and no unpleasant smell, 2 days ago i found few in other place under a tree, i dint know much about mushroom from description here these ones i think are yellow stainers, when cooked there was unpleasant smell but i ignored it and i added a little of to chicken meat and ate them, untill yesterday nothing happened, but yesterday night i fried most of them and ate them 1 hour nothing happened then i feel very thirsty i drink 2 cups of tea and i felt strange my stomach was like inflated i burped a little felt better but it was like i needed to burp more when i tried to burp myself something was coming like a puke and acid smell and i waited to burp automaticly not myself but after 4 hours i didnt burp and it look like mushrooms didnt digested my stomach felt like inflated then i scared mushrooms were toxic then i decided to make myself vomit so mushrooms come out i didnt have headache or anything else except inflated like stomach and feeling like to burp, i insert my finger near throat and made myself vomit and mushrooms came out , right now is lke 24 hours past since i ate mushrooms and i feel normal, do i have to see doctor? how long takes mushrooms to do the ill effects, and my main question was do yellow stainer also cause death or they have just a little ill effects?

    Reply
    • J C Harris
      J C Harris says:

      Hi Chris.
      Sorry to hear you had this experience. If they were Yellow Stainers you may have felt some of their effects with an upset stomach. A lot of people have no ill effects but some will experience these symptoms in varying degrees. If it has been 24 hours since your last meal with these mushrooms you should be OK and will have no more ill effects. Thankfully it was nothing worse.

      Reply
      • Chris
        Chris says:

        thanks, i read about other toxic mushroom effects it said they destroy kidney and else i was scared when i saw yellow stainer is toxic too, but its nice to hear yellow stainers are not deadly.
        telling the difference between yellow stainer and edible mushrooms that look like yellow stainer is very hard, they look like each other too much unless you cook them, then distinguishing them from smell is easy

        Reply
  20. Sam Ross
    Sam Ross says:

    Do yellow strainers stain skin an iodine colour where you’ve used your fingers to bruise the flesh? I was trying to ID a mushroom yesterday, but due to a cold haven’t been able to do a smell test, so I left well alone to be on the safe side. However, this morning I awoke with a brown iodine stain on my thumb where I was bruising the mushroom’s flesh? Is this normal for yellow stainers?

    Reply
  21. Fiona
    Fiona says:

    My parents bought some of these from a local farm shop as Horse mushrooms! We all realised as Mum was cooking them they absolutely STANK! They were binned instantly. The following day I bought a copy of the Roger Phillips book and that’s how I got interested in fungi.

    Reply
    • Ian Ford
      Ian Ford says:

      A great website with good tips. Like so many others I picked two nice firm ‘horse’ mushrooms this morning. Knowing about yellow stainers I tested the base of the stem and cut it in half. The faintest of yellow on the stem didn’t put me off totally but your advice to rub the edge of the cap showed bright yellow instantly. Very helpful though the colour faded quickly. My specimens were young.

      Reply
  22. Doug
    Doug says:

    Great site!

    I have a strange one- and an amazing new trick to help identify some bad Agaricus.

    I thought I had campestris and have had two meals of these in the last week, no ill effects but taste was not good. Thought maybe the way I cooked them, but mediciney might describe the taste. Thought I would try again, picked a very large bowl and prepared about a quarter of them 4 different ways. Taste was bad on all, but less bad on those that I battered and fried till crispy. Still not good though.

    Absolutely NO yellow staining! Crushed stem and crushed cap and gills smelled OK. Cooking smelled OK. Taste was bad, had to be my cooking…

    Back to the internet and found your page. Earlier found a page describing A. Cailfornicus, which is a member of the xantho section, but is described as slightly staining.

    As I researched, I started thinking horse mushroom due to the membrane pattern on the buttons and large size and slightly bulbous stem bottoms instead of narrowing.

    But the taste keeps insisting maybe Californicus, from the xantho section.? I live in NW Oregon and was not familiar with this variety, so I was sure mine were a good mushroom with no yellow staining whatsoever.

    Researching Californicus, I found a suggestion to hit the cut lower stem with some Lysol to bring out the yellow…

    So I am going to try the Lysol test to bring out the yellow, standby:
    Wow! Within about 15 seconds that stem turned a nice chromium yellow!

    So thought I would share this with your readers in case they run into this. Evidentally it is quite common in this area – I just never ran into it before.

    Lesson learned: All tests were ok, but bad taste… don’t assume it’s the cooking. Take a stem and cut in half, hit it with some Lysol and wait less than a minute. This works really well — amazing!

    Now to await the possible gastric distress for my newly acquired knowledge… Oh joy.

    Reply
    • J C Harris
      J C Harris says:

      Thanks Doug. That’s some great information there. And you had the patience to research and try the ID test. All very good. For us in the UK though I don’t believe we have the A.Californicus. I checked my Agaricus species list and it’s not there, although we do have similar looking species just as hard to properly identify. But thank you for the information – much appreciated.
      John

      Reply
    • DieselEstate
      DieselEstate says:

      Dear Doug,
      Thanks for the test details. Obviously, it will be really helpful. Only thing is: What is Lysol?
      BTW, the word is ‘evidently’.
      Regards.

      Reply
  23. Richard Barnes
    Richard Barnes says:

    I have been feeding my family and friends mushrooms from my garden for about 6 years. I get one crop about august-september. I recently found they are yellow stainers. I have eaten them every year and nobody has been ill. Must just be lucky. Today about to eat some definite horse mushrooms. yum yum.

    Reply
  24. Lawa
    Lawa says:

    Hello,
    Would like to go for a mushroom picking in the woods/ forest/national park. do I need a licence or permission from the landowner. If I do need if how and where can I apply for it.
    Thank you ,

    Reply
    • J C Harris
      J C Harris says:

      Hi Lawa
      Different land and forestry bodies have different regulations etc. I admit, these rules and regulations are not easy to find. As a general foraging (esp. mushrooms), follow these links.
      Firstly, see my ‘Mushroom Hunting’ page in the menu and scroll down to – ‘What about Foraging, Conservation and the Law?’
      Also, see here: http://www.foragingguide.com/mushrooms/articles/collecting/legal_aspects_of_picking_wild_mushrooms

      Do a search online for a particular wood or area of land you plan to forage on. And see if you can get answers from whoever owns it.

      It’s all a bit of a grey area and hard to know sometimes, but I hope this information helps.

      Thanks
      John

      Reply
      • Richard Barnes
        Richard Barnes says:

        I was wondering if the wildlife and countryside act 1981 might have something to say. Some fungi are as threatened as rare birds for example. Parts of Europe have stringent laws.

        Reply
      • Lawa
        Lawa says:

        Hi John,
        Thank you very much for your answer.
        It mean I done a licence?
        I’m really enjoying about mushrooms hunting but I do scare if someone stop me. I did looks online for few day to fine out how to apply for a licence, but I couldn’t get any information how and where to apply.

        Please if anyone know how to apply for it.

        Thank you,
        Lawa.

        Reply
        • J C Harris
          J C Harris says:

          Hi Lawa
          No, it doesn’t mean you require a licence. There is no generic (one for all) licence, as each place has different rules. Check with the local authority where you wish to go, and see if it’s OK to forage in their woods etc.

          Reply
  25. sarah
    sarah says:

    tonight i picked mushrooms,,,had tiny raw taste..
    normally would have spat out, but was so delicious-real mushroom taste, so didn’t..
    THey look like horse musromms but “flatter” top and thinner stems..
    Then nioticed yellow round rim of mushroom top..
    Any idea if this means they could be yellow stiners?
    THat wee taste was so yumy,,and here i am 5 hours later -just fine!
    not sure whether to enjoy for breakfast in morn!!!

    Reply
    • J C Harris
      J C Harris says:

      Field and Horse mushrooms do have mild yellow colouring here and there, depending on their age. If it was a Yellow Stainer it would be bright yellow (chrome yellow). If it was a nice flavour it may have well been one of the former.

      Reply
  26. Pam
    Pam says:

    I have just picked a basket full of field mushrooms (I think) but they were growing under some pine trees where the horses have been grazing and there is plenty of horse manure around.

    They look and smell like field mushrooms, but I’ve never found them under trees before?

    There are a lot of them, big and small. Look and smell like field mushrooms, no yellow staining.
    Dare I cook them? I’m dreaming of creamy mushroom soup.

    Reply
    • J C Harris
      J C Harris says:

      I wouldn’t think they’d be Field Mushrooms Pam, but maybe still an Agaricus species. Maybe Wood Mushrooms (Agaricus silvicola) which grow in large groups in all kinds of woodland. I haven’t a post on my site for this mushroom yet, but you can search online using the keywords above for more Identification information. Hope that helps.

      Reply
      • latchy
        latchy says:

        Ive found this thread as Ive eaten some mushrooms that my mrs brought home, her friend had picked them. they looked fine to me so I peeled them and noticed most of them had this yellow on them, but as I was looking forward to my mushroom ommelette i carried on regardless. As they were fried they turned yellow but I put this down to using rapeseed oil for the 1st time. the ommelette was a disappointment not at all tasty as expected but not bad enough to throw away. Now 5hrs later these pesky mushrooms are repeating with an unpleasant taste, lets hope thats as bad as it gets.
        Id never heard of yellow stainers before, they look as edible as any other mushrooms ive picked. Not a fungi to be with it seems

        Reply
    • Doug
      Doug says:

      See my post of Nov 21, 2015 on this same page… I have found that some yellow-stainers smell fine, don’t stain at all with cutting or crushing, but when cooked don’t taste quite right. Read about my experience and see a way of making sure with a little Lysol spray on a sample (yes, regular old Lysol). I ate several meals and did end up with some gastric discomfort but was OK. It did help me remember the lesson! :-)

      Reply
  27. Jeremy West
    Jeremy West says:

    I was part of a Mycological society years back and went on countless mushroom forays. For the most part, I know my mushrooms. Agaricus is tricky. Like others say, try the cooking test. I find a lot of Agaricus here in Colorado, and you need to know what exactly it is if you plan to try it. I collected some recently which did not stain at the base or anywhere on the stem, buy only stained a bit yellow on the caps when handled. Smell was pleasant. I cooked some, and while they didn’t turn yellow they smelled like some kind of chemical factory. When all tests fail, or you aren’t sure, cook the thing and see.

    Reply
  28. Ariel
    Ariel says:

    I feel some important points need to be made in relation to identifying this mushroom. In particular the degree of staining. I have some recently picked young ones in front of me:-

    The gills are definitely light pink, I have never seen white gills on these mushrooms even when young.

    They do stain a bit yellow on FIRST being bruised but after about 10 to 15 minuets this yellowing disappears, the bruising either disappears altogether or turns a light beige.

    The smell is quite indistinct, not long after picking a little unpleasant and I would go with inky, however when very first picked they do smell quite mushroomy, could be the smell of the mushroomy litter they grow in?

    Ultimate test is to cook them, they smell wrong in the pan.

    These are quite hard to spot in the field but the biggest giveaway is the ring which while being single is quite substantial and has an inner and outer frill.

    Shame I cant leave some pictures to show the points. Roger Phillips book has some good images and you can’t be too careful, last year I found a number of innocuous looking mushrooms that had volvas, they turned out to be Death Caps.

    I acknowledge that mushrooms can vary to some degree in appearance so your yellow strainers might be slightly different to those I have experienced over the years.

    Reply
    • J C Harris
      J C Harris says:

      Hi Ariel
      Yes, the staining can vary in strength, and as you say, it has to marked when fresh otherwise it fades. The gills are white initially, mainly when they’re covered by the veil when young. I agree, the smell on cooking is wrong. I sometimes can pick up the inky smell when they’re fresh.

      Reply
  29. Terri Metcalfe
    Terri Metcalfe says:

    Hi, a friend and I ate what I thought were horse mushrooms on Wednesday morning. They had a slight yellow tinge to the cap and pinkish brown gills which got more brown overnight (picked Tuesday afternoon). They had a faint mushroom smell, fairly pleasant, and only smelled more of mushrooms on cooking. They tasted fine. They didn’t bruise yellow on cutting at the stem (although I didn’t get the whole thing out of he ground) nor when I rubbed the cap (but the cap already had some yellow. Last night (Thursday) I became really ill with vomiting and diarrhoea and now am very weak and achey. My friend has diarrhoea too but no vomiting. I don’t understand as I was so confident they were horse mushrooms?

    Reply
    • J C Harris
      J C Harris says:

      It’s always tricky to be sure. The very base of the stem has to be dug out and sliced to see the chrome yellow for sure. The intensity of the yellowing on the cap differs a little. If the specimen is older it won’t stain as intensely. But as you have found these recently it makes me think it maybe a different Agaricus species. Also check out the Pavement Mushroom (Agaricus bitorquis) – https://bit.ly/2Mzg5hP – This is more common in late spring, mainly on roadside verges and of course near or out of pavements. This is edible, but there is a possibility you had a bad reaction. I always cook and eat a small amount every time I try a new edible species for the first time, just to make sure I’m fine with it.
      Anyway – I hope you and your friend feel better now. Take car.
      John

      Reply
      • Terri Metcalfe
        Terri Metcalfe says:

        Hi John, thanks so much for your reply and advice. We’re fine now, I’m just still perplexed by it! What you say makes sense although there wasn’t any soil on the caps and they were growing in grass. I’d also expect us to have become ill much sooner, this was 36 hours later. Perhaps a coincidental bug? I’m wondering if this link to my Instagram would work for a possible id!- https://www.instagram.com/p/ByAe2nDFc5bYAlfjAHtbpOlnQAiCHT356NorTw0/?igshid=p6i8zedpo2zm
        Thanks again!

        Reply
        • J C Harris
          J C Harris says:

          That’s the frustrating thing sometimes. It could have been a coincidence. Gastro symptoms (as far as I know) from mushrooms usually are within a few hours to 24 hours max. So I’m not sure. But the main thing is, you’re OK. PS. The link went to Instagram but is a private account, so I couldn’t view.
          All the best
          John

          Reply
  30. Daniel Shields
    Daniel Shields says:

    Thank you for sharing and spreading awareness! This article would help new mushrooms enthusiasts how to spot an edible mushroom from the deadly ones especially for people who would love to hunt mushrooms in the wild

    Reply
  31. Toni Dowrick
    Toni Dowrick says:

    Thank you so much for the guide…
    I’m in Cornwall UK, south coast. Picked a good 2 or 3 kilos of what I thought were field mushrooms yesterday (they were in an old pasture field on a cliff path).
    Your test of “bruising the cap” saved us from certain tummy troubles!!
    I’d love to send you the photos if you wish to use them?

    Reply
    • J C Harris
      J C Harris says:

      Sorry for the delay Toni. If you have good pictures of them I can see if I’ll use them. My inbox is very fully at the moment, so I’m flooded with enquiries, it may take time to view them.
      All the best
      John

      Reply
  32. Jeanette
    Jeanette says:

    I think we have just has these yellow stainers for dinner with garlic masala and cream. They did actually taste wonderful , but now panicking as we originally thought they were field mushrooms until my friend told me about these yellow stainers. How long do these side effects kick in and will drinking milk help

    Reply
    • J C Harris
      J C Harris says:

      Sorry for late reply. I wouldn’t worry too much. I know several people who have eaten them and been fine. If you do have a reaction, it’s usually from 2-6 hours after consumption (as a guesstimate average). I don’t think the milk helps though. I would just recommend a lot of water. It varies from person to person. I hope you were fine.

      Reply
  33. SANDY ROSE
    SANDY ROSE says:

    One of the best blogs I have ever seen. The way you give the definition of the mushroom is really interesting. It includes huge information. I appreciate your thinking. Thank you so much.

    Reply
  34. Richard Gill
    Richard Gill says:

    I have frequently eaten pavement mushrooms or horse mushrooms. They show a little yellow colouring but they don’t turn yellow on bruising. They do turn yellow when you fry them. A bit disconcerting. But: they smell and taste good, mushroomy, both before and after cooking! I can’t discern an aniseed smell, so they are not horse mushrooms. Or my sense of smell is not what it was. I’m a 70 year old male. I’m a very cautious mushroom forager, have been doing that intensively for 10 years. Eaten these ones lots of times. Never yet met a “yellow stainer” (smell of carbolic acid, disgusting taste).

    Reply
      • Malcolm boultby
        Malcolm boultby says:

        Thought I had some Horse Mushrooms just cooked and ate a smallish one, cannot say it was the best taste. Decided to do more reseach after the event and read more about them. When I cut the cap and also rubbed it it did turn yellow which is slightly worrying. Hope no long lasting effects and have already cancelled the ambulance.

        Reply
  35. Jake F
    Jake F says:

    Good information thank you

    I picked some yellow stainers at the weekend and ate a tiny sliver of one cooked. I thought these were field mushrooms although they had a bit of yellow at the base when cut. I had read that the smell is the main identifier and these smelt mild but good. The day after I showed these to my partner and she said they stank of chemicals!! I thought i had a reasonably good sense of smell but it seems like i am totally unable to smell whichever chemical is responsible. I thought this was interesting enough to share in case it stops anyone else from eating them.

    (No ill effects btw but it was a tiny piece)

    Thanks

    Jake

    Reply
    • J C Harris
      J C Harris says:

      Hi Jake.
      The ‘smell’ factor is something some people sense well, and others don’t – to me, I smell the mildly unpleasant chemical odour (like your partner).
      Glad there were no ill effects.

      Reply
  36. EM MORRIS
    EM MORRIS says:

    I found some horse mushrooms in the UK. At least I think they are after checking the comments. They smell nice. I also found some Trooping Funnel mushrooms in a different location. I also think I will give them a try.

    Reply
    • J C Harris
      J C Harris says:

      Nice. Just be careful with the Horse Mushrooms – I hope that they are.
      Trooping Funnel has a strong flavour when older and best in stews or soups. Younger examples are better to eat on their own after cooking.

      Reply

Trackbacks & Pingbacks

  1. […] tree line. There was no stark, chrome yellow staining as I scored the flesh, so they weren’t Yellow Stainers either. Horse Mushrooms […]

  2. […] of his wild mushrooms forays, especially as last time I picked some mushrooms they turned out to be Yellow Stainers. And no, I didn’t eat […]

  3. […] an extremely common look alike that could cause nasty gastro upsets (read all the about the Yellow Stainer in this post). In fact, some Agariucus xanthodermus were quite happily growing on a grassy verge […]

  4. antelope landowner tags…

    The Mushroom Diary – Wild UK Mushroom Hunting Blog » Blog Archive » Horse & Field Mushroom Imposter! – The Yellow Stainer…

  5. […] I just wanted to point out and exaggerate the identification tips of this beautifully edible UK mushroom. As well as the typical large white ‘mushroom look’, I’ve shown in the pictures the distinctive mature dark brown gills (that of an older specimen, pink when younger), and the ring zone two thirds up the stem, which is very small, sometimes indistinct! So this helps in identification, as the Yellow Stainer mushroom (a sinister, but not deadly twin) has a much larger, floppy ring zone. See my post on the Yellow Stainer mushroom. […]

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