from Greek meaning 'yellow-skinned'
Overall: a poisonous mushroom which resembles a number of edible agaricus species, therefore extra care should be taken if you are planning on eating species such as Field Mushroom (Agaricus campestris) or Horse Mushroom (Agaricus arvensis).
Stem: the same colour as the cap, the base of the stem is often very yellow and certainly obvious if cut in half.
Flesh: white with yellowish tints, the base of the stem is strongly chrome yellow which is noticeable when cut in half.
Gills: start quite pale, almost white, becoming pinker and then grey-brown with age. Often smell of ink.
Cap: white, but drying more of a buff colour, starts of convex and becomes flatter with age, the cap margin becomes yellow quickly when handled or rubbed but the more central parts of the cap can too. Smells of Ink.
Note: statistically the species of mushroom that poisons the most people, symptoms include vomiting and diarrhoea and even comas in some people.
OVERALL: Of all the mushrooms that people accidentally poisonous themselves with, the Yellow Stainer is the most likely. People often confuse it with the edible Field Mushroom (Agaricus campestris) and symptoms vary from the usual vomiting and diarrhoea to some cases of people going in to comas, to some people having no reaction at all! I believe this species is on the increase, I am seeing it more and more frequently and in places I never us to find them, it is one to learn to avoid, it smells of ink and becomes stronger when you cook it, it turns yellow and has a large ring on the stem (in proportion to the size of the stem). People often say they only pick Field Mushrooms but in a survey we carried out most people who collected Field Mushoooms were often collecting Field Mushroom look-a-likes which happen to also be edible. For this reason if you are going to go out and pick Field Mushrooms then learn this species first!
HABITAT: often under hedgerows, in gardens and sometimes meadows (making it likely to come across it if picking Field Mushrooms).
DISTRIBUTION: Found throughout the UK, seems to be increasing.
SEASON: Early Summer through to Autumn.
EDIBILITY: POISONOUS, usually causes vomiting and severe stomach cramps but has also put people in to comas. Some people have no reaction.
EASE OF IDENTIFICATION: The colour change when you rub the cap or the base of the stem along with the ink smell and relatively large ring on the stem should be enough to make an identification of this species.
SMELL: of ink and becomes stronger when it is being cooked.
SIMILAR SPECIES: Most of the Agaricus family, the Inky Mushroom (Agaricus moelleri) has a darker mottled cap but also turns yellow when damaged.