well, it's wood stained teal by this mushroom -- very cool and used to be found a lot more commonly in a particular spot in Fox Park before I started collecting it from time to time...
Green lichen on a tree trunk
Multiple samples of species within one location
Chlorociboria aeruginascens is a saprobic species of mushroom, commonly known as the green elfcup or the green wood cup because of its characteristic small, green, saucer-shaped fruit bodies. Although the actual fruit bodies are infrequently seen, the green staining of wood caused by the fungus is more prevalent.