Three fungi collected from 3 dead logs in the same general area. Each medium size, connected to the wood at the side (no stalk), more or less well defined concentric ridges in the outer part. The underside of each shows a "gill-maze" pattern and the pattern seems identical in each fungus. The center parts of the fungi vary. I suspect these are all the same species but am not sure what the variation in the central color and consistency means. In the one with the black center, the center is considerablly raised and seems granular. Could these be algal deposits?