A small to medium bracket fungus growing to about 6 or 7cm. The edges in particular tend to show some yellow colouration especially when bruised or scaratched, sometimes has a green algae coat when mature.  The under surface is smooth and without pores.  The point of attach chment to the substrate is often narrow, but this is not diagnostic unless used in conjunction with other characteristics

Stereum hirsutum is similar; smaller, more hairy and does not stain yellow.  

yellow stain

You must photograph the undersides as well as the upper, showing any staining when fertile surface scratched.  Note host and substrate

On the dead wood of broadleaf trees, often in well wooded areas.

Widespread and fairly frequent in England and Wales.

Fairly frequent in Leicestershire and Rutland.