Members of the Crepidotus genus are shelf-like gilled mushrooms that superficially resemble oyster mushrooms, but are much smaller than oyster mushrooms and have brown rather than white spores. Creps are round or kidney shaped in outline and have no stalk or a rudimentary stalk.
Cosmopolitan and found throughout North America, creps are saprophytic (feed on decaying wood) and grow scattered or in groups on fallen herbaceous debris, usually hardwood logs, branches and twigs (especially oaks).
Crep species are often separated by spore shape and can only be identified by microscopic observation. This mushroom, which I believe might be C. malachius, has a white surface, and close to distant gills turning brownish as the fungus ages.
Creps are not known to be poisonous, but are so small that they are not worth the effort to collect and eat.
I like creps – they glimmer on the dark forest floor like little white gems. These tiny creps were photographed near Burney Creek (Shasta County CA).