Psilocybe semilanceata, commonly known as the liberty cap, is a small mushroom that contains the psychoactive compound psilocybin. It typically grows in grassy fields and meadows, particularly in areas with rich soil. The mushroom has a distinctive conical or bell-shaped cap that can range in color from yellow-brown to olive-green. This species is widely distributed across North America and Europe, often appearing in the fall. Psilocybe semilanceata is known for its potent effects, which can include altered perception and mood changes. It is important to note that the collection and use of this mushroom may be illegal in some regions.