...have no:

clue about what this is...

I think it is a chicken mushroom, growing an a dead stump of a Robinia, with lots of mysterious dark, hard, graphite like 'bubbles' around. They seem to grow out of the mushrooms, like out of little pimples which bursts open, birthing a baby bubble which grows then bigger on top of the mushroom.
Have a closer look over here.

Or is it just my imagination? I hope for your help.

Another hot and muggy day, the promised heavy thunderstorms turned into steady boring rain. So you get a mushroom blip.
Have a fab friday night and keep warm, frost is predicted!