Leucoagaricus leucothites  (Vittad.) Wasser (1977)
Syn: Leucoagaricus naucinus

This white Leucoagaricus is truly Cosmopolitan. I see it from the parks of Europe to Berkeley, California in the same diversity of statures appearing within the same patch. To the uninitiated who probably didn't notice it's collar-like annulus it may even appear as a white Amanita.