Bitter oysterling mushroom - Panellus stipticus

"Panellus stipticus", commonly known as the bitter oyster is a species of fungus in the family Mycenaceae, and the type species of the genus "Panellus". A common and widely distributed species, it is found in Asia, Australia, Europe, and North America, where it grows in groups or dense overlapping clusters on the logs, stumps, and trunks of deciduous trees, especially beech, oak, and birch.