Cultivated in petri dish using potato dextrose agar. Indoors.
Growing on Amanita muscaria
on a cherry tree
I feel pretty good about this being something under Brodo et al.'s entry for Placidium lacinulatum, and the apparently black lower surface seems to indicate P. lachneum. This was appeared to be on a rock, but when I tried to look at the lower surface it appeared to be attached to a clump of soil.
If I've got the ID right here it's pretty interesting b/c Brodo et al. say this lichen likes calcareous rock, and the rocks up there are packed with fossilized bivalves. Apparently umbilicate, lower surface smooth.
Substrate Quercus garryana, JBLM