Collybia cirrhata

This is a key to gilled mushrooms, that is, mushrooms having a definite cap with a fertile surface consisting of gills. The fruiting body usually also has a stem, although that may be lateral or absent (usually, then, the mushroom is growing from wood). You can use this key to identify mushrooms that you find.

Fruiting body containing fibers (usually in the stalk)

Spore print "light-colored": white or buff, sometimes tinged with pink or tan. Greenish and (except for the Russulales) yellow spore prints also go here
Stalk fibrous, not fracturing like a piece of chalk

None of the special features distinguishing the other white-spored genera:
Gills not free, as in the Lepiotas and Amanitas
Basidia not extra-long, as in the Hygrophoraceae
Spores smooth, except for Lentinellus

Cap less than an inch across
Growing on other fungi, usually on their blackened and squishy remains

Tiny cap (less than 1/2" across) on a proportionately very long stem with at least two of the following four characteristics:
1) Numerous short side branches, bearing conidia on their swollen ends
2) Arising from a small, lumpy (about pea-sized) sclerotium which is embedded in
3) the (mushroom) substrate, usually decaying Russula or Lactarius species
4) Entire fruiting body with a pale orange or pink tinge

Collybia cirrhata     (Persoon) Quélet