Agaricus californicus or California Agaricus

Description: Shiny, white to brownish cap with unpleasant-smelling gills; in urban areas.

Cap: 2-4" (5-10 cm) wide; convex to flat; dry, smooth to somewhat scaly, shiny; white or brownish over center; yellow with KOH. Odor pungent.

Gills: free, close, narrow; whitish at first, becoming bright pink and eventually dark brown.

Stalk: 1-4" (2.5-10 cm) long, 3/8-5/8" (1-1.5 cm) thick; whitish, darkening on handling; dry, smooth.

Veil: partial veil membranous, white; leaving persistent, pendant ring on upper stalk.

Spores: 4-7 X 3-6 m; elliptical, smooth, purple-brown. Spore print dark-brown.

Edibility: Poisonous

Season: September-November, year-round in wet areas.

Habitat: Scattered to several, in urban areas in lawns and parks.

Range: California

Look-alikes: A. campestris does not react with KOH or develop a pungent odor.

Comments: A "dead ringer" for the edible Meadow Mushroom (A. campestris), this common California mushroom is often mistaken for it; the resultant poisonings are mostly gastric upsets.

Agaricus californicus image and excerpt from Gary H. Lincoff's National Audubon Society Field Guide to North American Mushrooms, (1981/2004, p. 504, image #151).

Agaricus californicus (California Agaricus)