Split gill

Schizophyllum commune is a very common species of mushroom in the genus Schizophyllum. It is the world's most widely distributed mushroom, occurring on every continent except Antarctica.
Although European and US guidebooks list it as inedible, this is apparently due to differing standards of taste rather than known toxicity, being regarded with little culinary interest due to its tough texture. S. commune is, in fact, edible and widely consumed in Mexico and elsewhere in the tropics. The authors explain the preference for tough, rubbery mushrooms in the tropics as a consequence of the fact that tender, fleshy mushrooms quickly rot in the hot humid conditions there, making their marketing problematic.
The gills, which produce basidiospores on their surface split when the mushroom dries out, earning this mushroom the common name Split Gill. It has more than 28,000 sexes.
It is common in rotting wood, but can also cause disease in humans. (information from Wikipedia)