Sheathed Woodtuft

Kuehneromyces mutabilis

Its species name mutabilis means "changeable" — and it's fitting in more ways than one. The caps look dramatically different depending on moisture: when wet they're smooth, greasy, and dark brown, but as they dry they fade from the center outward, creating that "two-toned" look that gives it names like "two-toned woodtuft."