Bitter Oysterling - Panellus stipticus

The cap is kidney shaped to shell shaped and tan or pale ochre, with a velvety or felty upper surface that is often broken up into small patches.  It has a short, tapering lateral stem. The gills are crowded, forked and also cream or tan/ochre; usually with distinctive cross veins.  Spore print white.

At first glance this may be mistaken for a bracket, but the presence of gills indicate an agaric. 

Photograph from top down and from underneath to show gills and stem; note habitat and substrate.

Trunks, large branches and stumps of dead hardwood trees, particularly oak, birch, alder, beech.

Mainly autumn and early winter in Britain.

Widespread and fairly frequent in Britain.

Fairly frequent in Leicestershire and Rutland.

https://www.first-nature.com/fungi/panellus-stipticus.php