What is "collybia"

Collybia (in the strict sense) is a genus of mushrooms in the Tricholomataceae family. The genus has a widespread but rare distribution in north temperate areas, and contains three species that grow on the decomposing remains of other mushrooms.

Until recently a large number of other white-spored species, some very common, were assigned to this genus, but now the majority have been separated into other genera: Gymnopus, Rhodocollybia and Dendrocollybia.