Agaricus xanthodermus, commonly known as the yellow-staining agaricus, yellow-staining mushroom or yellow-stainer, is a mushroom of the
genus Agaricus, which displays a strong yellow colouration at the base of the stem when cut. It has a phenolic smell. It is poisonous for most people, causing gastrointestinal upset, but can be eaten by some without apparent negative effect.