Amanita pachycolea, commonly known as the western grisette, is a species of agaric fungus in the family Amanitaceae. It was recognized as a distinct species by mycologist Daniel Elliot Stuntz, and published in 1982 by Harry Delbert Thiers. Found in western North America, it associates with conifers in coniferous and mixed forests. Amanita pachycolea is classified in Amanita section Vaginatae, which includes species with conspicuous radial striations on the cap, inamyloid spores, and the absence of a ring on the stipe. The mushroom is edible, but not recommended due to possible confusion with toxic Amanita species.