A white woodland Agaricus whose stem ends in an abrupt, flattened bulb. The cap yellows with age and where it is rubbed, and the mushroom smells strongly of almonds. Kerrigan's 2016 monograph of North American Agaricus treats it as a distinct species in the pale woodland group of section Arvenses, separate from A. sylvicola.
Edibility is poorly documented. Some older sources call it edible, but MushroomExpert.com gives no edibility information for the modern, narrower species concept, and the species is reported to accumulate cadmium. Not recommended. Deadly white Amanitas such as A. bisporigera can also have a bulbous base. Amanitas keep white gills and drop a white spore print, and their bulb usually carries a cup-like volva. Full safety details in notes.
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Habitat
Saprobic, in groups in hardwood forests and in urban plantings under ornamental Norway spruce; fruits in fall.
Distribution
North America. Kerrigan (2016, as summarized on MushroomExpert.com) documented it from Pennsylvania, New York and Washington, and the MushroomExpert collections are from Illinois. Wikipedia also lists reports from Mississippi, Quebec, Germany, China and India, but those records may reflect older, broader uses of the name.
Characteristics
Cap: 5-9 cm, convex to bell-shaped and later nearly flat; dry, nearly smooth to finely fibrillose; white, aging and bruising yellowish; KOH turns the surface yellow. Gills: free, crowded, white at first, then grayish and finally dark brown; covered when young by a whitish partial veil that stains yellowish. Stem: 5-10 cm long and 0.5-1 cm thick, smooth and whitish, equal down to an abruptly bulbous base; white to yellowish ring; bruises yellowish toward the base. Flesh: white, not changing when cut. Odor: strong, of almonds. Spore print: dark brown. Spores: 6-7 x 3.5-4.5 µm, ellipsoid, smooth (MushroomExpert.com).
