Cap 7-20 cm broad, subglobose to pulvinate, becoming convex to nearly plane in age; surface dry, brown, smooth, breaking up into coarse, brown, concentrically arranged scales except for the disc where the cuticle remains intact; margin inrolled at first, frequently appendiculate; flesh thick, white, discoloring yellow-orange, darkening to reddish-brown.
Gills white, close, free, staining brown in age.
Stipe 6-16 cm long, 2-3 cm thick, enlarged to abruptly bulbous at base; smooth, white, bruising brown; veil white, thick, breaking to form a well developed, movable, double lipped superior annulus.
Spores 8-10 x 5-7 µm, ovoid, smooth, dextrinoid, with an apical germ pore. Spores print white.
Solitary to gregarious, sometimes in cespitose clusters, fruiting spring, summer and fall; common in lawns, gardens, and near compost heaps; also under Monterey cypress and Eucalyptus. Summer fogs are often sufficient to trigger fruitings along the coast.
Edible and choice, but a few allergic reactions have been reported.
Chlorophyllum brunneum, with its coarse brown cap scales on a white ground color, free gills, and bulbous base is a distinctive mushroom. Nevertheless, care should be taken to avoid mistaking it for a toxic Amanita species. Some Amanita species have cap warts (remnants of a universal veil) superficially resembling the scales in Chlorophyllum brunneum, but these can be easily rubbed off, while the scales in the Shaggy Parasol must be torn off. Additionally, Chlorophyllum brunneum, while having a bulbous base, lacks the true volva of an Amanita. Chlorophyllum molybdites, a cousin of the Shaggy parasol, is a toxic species and similar in appearance, but mature specimens can be told apart by their olive-green gills and spore print. It is rare in the S.F. Bay Area, preferring the warmer climate of California's Central Valley and Southern California.