Underside of Mystery Mushroom coming out of log with dark brown spore prints (2 of 2)

Description:

Here is the underside of the previous picture of the caps. Note the fuzzy white base, thin stem (hollow), buff crowded gills, chocolate brown spore prints.

Habitat:

log at Prospect Park

Notes:

there are fragments along the margins of the caps. Does that make it a Psathyrella or Panaeolus? Do they grow out of logs? It's also hard to say what kind of brown the spores are, they're very dark brown, like a dark-chocolate bar, but could it also be purple-brown? Don't know.