This one looks like something from a horror film
Caution: Do NOT use iSpot to identify fungi to eat!
Some fungi are very poisonous so a mistaken ID could have serious consequences.
No interactions present.
I'd say about 8 inches, 20 cm across. Can't say tree type, it's been on the ground too long, but it's in mixed deciduous woodland with a preponderance of beech, but alse oak, sweet chestnut, birch etc
Paul Seligman. Flickr: http://www.flickr.com/photos/paul_seligman_cardiff/collections/721576087...
Lat/Lng: 51.48411, -3.25295
OS grid ref: ST130768