Agaricusarvensis – horse agaricus, horse mushroom, prairie mushroom Gives off a smell of aniseed or almonds when young. Flesh is white to cream but bruises yellow. Cap is smooth to slightly scaly while the stem is smooth with a ring. Gills start out grayish-pink but become chocolate-brown.
Agaricusaugustus – giant agaric, horse agaric, prince agaricus, the prince
Agaricusbernardii – salt-loving agaricus, salt-loving mushroom Stout and white to being with but usually develops grayish cracks or scales on cap. Gills begin pink and turn chocolate-brown. Stipe has an upturned ring and a sock-like base. Flesh turns reddish brown when cut and may develop a fishy or briny smell.
Agaricusbisporus – champignon, button mushroom, commercial mushroom, cultivated mushroom Generally brown cap with flat feathery scales. Gills begin as pink but turn chocolate-brown. Stem is white and smooth with a slight ring. Flesh may turn pink when cut.
Agaricusbuckmacadooi Usually large size up to 7" cap diameter and 8" tall, very dark brown appressed fibrils / fine scales on the cap surface, flesh of stem may become slightly yellowish in lower part near base, a rubbery, thick-margined ring that is pendant and intermediate, phenolic odor, no staining, and yellow KOH reaction. Recorded in the Puget Sound area and Olympic Peninsula. Pacific Coast of North America, in Washington and California.
Agaricuscampestris – meadow agaricus, pink bottom, champignon, common field mushroom, hot-bed mushroom, meadow mushroom The popular edible meadow mushroom, as both its scientific and common names suggest, is usually found in fields or pastures (campestris means growing in a field in Latin), especially those rich in manure. The largest fruitings tend to occur when warm and wet weather coincide. It is a stocky, medium-sized, clean white mushroom with bright pink gills when young (another common name is pink bottom); however, as it ages it tends to become brown overall with dark chocolate gills. The cap may be somewhat fibrillose to scaly and, typically, the cuticle extends past the margin, like an overhanging table-cloth. The ring usually is thin and not persistent, and the base of the stipe often is tapered. It occurs nearly worldwide. Worldwide
Agaricushondensis – felt-ringed agaricus, felt-ringed mushroom Agaricus hondensis is a medium to large toxic species, with an often pink-tinged, fibrillose cap that darkens with age, solid flesh, smooth stipe, and a large thick (“felty”) ring. The gills are grayish to pale pinkish when young, and the stipe base usually bruises light chrome yellow and exhibits a phenolic odor when the flesh is crushed.
Agaricusmoelleri Agaricus moelleri, usually known as A. praeclaresquamosus (Freeman), is another phenol-smelling, toxic species and is the most common of this group in the PNW. It is a medium to medium-large species with a marshmallow-shaped cap and pallid gills when young, dark gray-brown fibrillose cap, smooth stipe, and well developed ring. It lacks the pinkish tints and markedly solid flesh of A. hondensis, and the flesh in the extreme base of the stipe stains a brighter yellow when cut or crushed.
Agaricussilvicola – forest agaric, sylvan agaric, woodland agaricus, woods agaricus, sylvan mushroom, wood mushroom The key features of Agaricus silvicola are its medium-large size, overall whitish color, tendency to stain yellow on cap and stipe, pleasant (though sometimes very faint) anise odor, and occurrence in forests (silvicola is Latin for forest-inhabiting). It is probably the most frequently encountered agaricus in our woodlands. The name A. abruptibulbus has been applied to forms with bulbous stipe bases, but variation in stipe shape is so great that use of this name has been largely abandoned. Broad
Agaricussubrutilescens – wine-colored agaric, wine-colored agaricus, woolly-stemmed agaricus, woolly-stem Agaricus subrutilescens is a highly esteemed edible mushroom although, like most agaricuses, it is not for everyone. It is a tall statuesque forest-dweller, with a whitish cap overlain with purplish brown fibrillose scales, shaggy white stipe, and persistent, but not especially heavy, skirt-like ring. The flesh is whitish, non-staining, and has a mild odor. The gills are whitish at first, then turn pale pinkish, and finally chocolate-brown. It is not uncommon, but usually does not occur in large numbers. If not restricted to the Pacific Coast, at least it is most common here.