Yellow Stainer

Description

Most books illustrate the 'normal' white smooth capped form, but if forming under dry conditions then the cap can be 'scaly' and darker. Some authors refered to this as var. lepiotoides. 

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).

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!