The cap center has brownish scaling.  Yellowish to brownish droplets develop on underside of the annulus. Persistent ring. Bruises yellow at base. Saprobic. Yellow KOH reaction. Phenolic or no odor. The only known deadly agaricus grows in Africa, Agaricus aurantioviolaceus.  031-001

« Worldwide there may be up to 300 species of Agaricus, some of which are edible, while others are poisonous. Our common button mushroom, Agaricus bisporus, is in this group. So is Agaricus campestris, the field mushroom. All agaricus have a fleshy cap, radiating gills, and a chocolatey brown spore-print. They also have a stipe and a partial veil which becomes a ring on the stalk. Agaricus arvensis is called the ‘horse mushroom.’ It has a sweet smell, cog-wheeled ring. The caps will often bruise yellow if rubbed, and the flesh will sometimes turn yellowish on exposure to air--but the flesh in the base of the stem is not yellow, which helps distinguish it from other species. 030-001
EDIBLE MUSHROOMS & POISONOUS LOOK-A-LIKES by Dianna Smith
Saprobic. Found along roadsides, grass, disturbed ground. Cultivated in China. Coprine, which has unpleasant consequences if consumed with alcohol, is found in Coprinopsis atramentaria, but not Coprinus comatus. Coprinus comatus has also been found to kill two different nematode species! Coprinus comatus is more closely related to Agaricus and Lepiota than it is to the other dark-spored, ink producing, deliquesing mushrooms like Coprinopsis atramentaria and Coprinellus micaeus! 032-001 »