Trametes versicolor
These images show the blue variety of Trametes versicolor, a polypore
mushroom.  This fungus can be used as a natural dye.  Most often this
fungus exhibits brown and orange coloration.  Grows from wood, including
oak and beech.  Turkey Tail is a common name.
See Trametes versicolor at
Fungi Growing on Wood
Fungus of the Month at
Tom Volk's Fungi