Mycena with Pseudorhiza

A pseudorhiza is similar to a root. These are all from Smith's monograph on Mycena.
Mycena species with a pseudorhiza:
M. bryophila
M. galericulata
M. kauffmanii
M. lasiosperma
M. maculata
M. megaspora
M. nodulosa
M. radicatella
M. wyomingensis
Sometimes a short pseudorhiza:

M. rugulosiceps