Becoming familiar with wild fungi has been a slow, deliberate process for me. With few exceptions (like Black Trumpets), I've focused my efforts on species who grow on or at the base of living or dead trees. One such wood eater is Artist's Conk (Ganoderma applanatum), a species who can grow quite large (more than 2' across) and lives throughout the United States.
Last week, I drove by this newly broken Artist's Conk shelf attached to an Ash-leaved Maple (Acer negundo). I stopped to take a closer look and noticed two distinct layers of pore tubes revealed by the break. Artist's Conk shelves are perennial and add a layer of pore tubes annually, which allows them to be aged.
The common name of this polypore refers to the mushroom's pore surface, which darkens when etched and can be used by artists as a natural medium (an image search for Artist's Conk art will lead you to some fine examples). This species is also used medicinally (as a tea or tincture), though its close relatives Red Reishi (Ganoderma lucidum) and Hemlock Reishi (G. tsugae) are more well-known in this regard. To see many more photos and learn more about Artist's Conk, check out the webpages of David Spahr and Michael Kuo.