Yellow stainer mushrooms

Agaricus xanthodermus, the Yellow Stainer, can cause serious stomach upsets and so should not be eaten. It can be confused with other members of the Agaricaceae. No other common white mushroom turns such a bright chrome yellow so rapidly when handled, although a few of the edible Agaricus species do bruise slightly yellow, and so it is important to check all characteristics, including odour, when making an identification.