Life on a dead stump

These are, I think, Lemon Discos Bisporella citrina, a fungus with tiny (<4 mm) saucer shaped fruit bodies. This is a highly gregarious species growing in dense swarms on the dead wood of deciduous trees.
If you go large and look carefully you might be able to make out that much of the rest of the stump is covered in a colony of a black, globular slime mould. Towards the bottom of the photograph there are also a few purplish Beech Jellydiscs  Neobulgaria pura. There is a lot of action on a dead stump in the Autumn!