I found this at he bottom of an old tree stump, can't remember if it was and alder or a willow. Does nyone now what it is?
That would be probably something in the genus Trametes. There are a bunch of species names, the most common being versicolor.
Doesn't look like versicolor. Cerrena unicolor maybe ? http://www.mushroomexpert.com/cerrena_unicolor.html