At first glance, I thought this was Turkey tail, a common bracket fungus that I’m sure most people are aware of.
But, when I looked more closely, particularly at the newest growth – those fat, juicy looking little buttons, and also at how furry some of the growth was, I knew my initial impression was wrong. This is Tripe fungus (Auricularia mesenterica).
I couldn’t tell what the wood was as the tree had been sawn off very close to the ground and only a very short section of trunk and some sections of exposed root remained (all of which were covered in fungal growth). But, Tripe fungus grows most commonly on Elm trees so I assume this was an English elm that had succumbed to Dutch elm disease.