Members of Agaricus are characterized by having a fleshy cap or pileus, from the underside of which grow a number of radiating plates or gills, on which are produced the naked spores.

Members of Agaricus also have a stem or stipe, which elevates it above the object on which the mushroom grows, or substrate, and a partial veil, which protects the developing gills and later forms a ring or annulus on the stalk.

It possibly originates from ancient Sarmatia Europaea, where people Agari, promontory Agarum and a river Agarus were known (all located on the northern shore of Sea of Azov, probably, near modern Berdiansk in Ukraine).

[22] It was eventually identified as sclerotium of the crust-forming bark fungus Ceraceomyces tessulatus, which is not particularly closely related to Agaricus.

In addition, the scientific names Agaricus and – even more so – Psalliota were historically often used as a "wastebasket taxon" for any and all similar mushrooms, regardless of their actual relationships.

Species either confirmed or suspected to belong into this genus include: A notable group of poisonous Agaricus is the clade around the yellow-staining mushroom, A.

In Agaricus, by contrast, the gills are only initially white, turning dull pink as they mature, and eventually the typical chocolate-brown as the spores are released.

[52] The species most often sold as such quack cures is A. subrufescens, which is often referred to by the erroneous name "Agaricus Blazei" and advertised by fanciful trade names such as "God's mushroom" or "mushroom of life", but can cause allergic reactions and even liver damage if consumed in excessive amounts.

[53] The genus contains the most widely consumed and best-known mushroom today, A. bisporus, with A. arvensis, A. campestris and A. subrufescens also being well-known and highly regarded.