Marasmius nigrodiscus 

Marasmius nigrodiscus01502

Marasmius nigrodiscus (Peck) Halling 1983

has a white to cream-colored thin cap which can be fairly large with a darker brownish central bump and a faintly lined margin. Whitish attached gills become tannish-gray with age. The stem is tough. Spores are white. It is a saprotrophic fungi that breaks down leaf and needle litter summer through fall. It is in the Marasmiaceae family of the Agaricales order.