Lepiota helveola
Lepiota helveola is a gilled mushroom of the genus Lepiota in the order Agaricales. It is known to contain amatoxins and consuming this fungus can be a potentially lethal proposition. It was described by Italian mycologist Giacomo Bresadola in 1882.
It has white gills and spores. They typically have rings on the stems, which in larger species are detachable and glide up and down the stem.