Often glibly called “the Meadow mushrooms”, about 90% of Agaricus species actually reside in forest and other non-grassland habitats. This group includes Button mushrooms, Meadow mushrooms, Almond mushrooms, Horse mushrooms, Princes, Emperors, Bad Angels, Torqs, and their many, many allies. All species exploit the partly decomposed remains of green plants, and some species are edible. This volume, the result of 40 years of work by R. W. Kerrigan, is a monographic technical resource covering all that is currently known about Agaricus in North America. Both authoritative and remaining generally accessible, it evaluates Agaricus diversity in terms of living members of natural ecosystems, and as elements of a complex pattern of phylogenetic relationships. Setting aside technical information, this volume could also serve as a field guide. Includes keys, descriptions, photographic images, and habitat and use information.