ATL #7, also known as Atlantis #7 is a strain of Psilocybe tampanensis. P. tampanensis is native to the United States and Mexico, and it produces both mushrooms and sclerotia (also called truffles) that contain psilocybin, a psychoactive compound that causes hallucinations and altered perception. 
ATL #7 fruits have caps that start out as a small and convexed in shape, and they flatten out as they mature. The caps are a shade of reddish brown at the center.