Pluteus pellitus
Cap characteristics separate this species from Pluteus cervinus and
Pluteus petasatus, two species that grow in similar habitat.  The cap
Pluteus pellitus is mostly white, smooth, silky and slightly visid.  This
single specimen was growing in May from a decaying hardwood log.
Typical cystidia (microscopic cells on gill surface) of Pluteus pellitus.
See Mushrooms Demystified,
David Arora, 1986, p. 256