OK, it probably isn't but I haven't the faintest idea what else it could be.

Growing at the base of a big Oak tree close to Lower Brockhampton Manor (National Trust) in Herefordshire.
The older brackets were hard on top and looked almost to be varnished, hence my guess.... The newer ones were softer with pale creamy pore surface while the older ones had browner pores.
As this was a very public and busy place, I didn't like to start poking about too much or trying to break bits off!
I will be grateful for any suggestions as to ID. Thanks!
Pore surface of older brackets and upper surface of fresher ones:
Cap, edge & pore surface of newer brackets:
Forgot to say - these were taken on 10th September on a warm and sunny day in the midst of a dry few days.