Here's an easy to recognize polypore that is both edible and not:

The flattened (but sunken near the stalk), nearly circular to kidney-shaped caps, which often overlap, can become huge when mature, 2-3/8 to 12 inches across. They're dingy yellow-brown to brown on top, with darker, overlapping scales. The flesh is white.

Underneath, the pore surface is off-white to yellowish. The pores are large enough to see without magnification, and they run down the upper part of the stalk.

The spore print is white, and often, the surface of a cap is covered with this white powder from the cap above it.

The thick, stubby, lateral stalk is 3/8 to 2 inches long, the same color on top as the spore surface, but black near the base.

The mushroom's shape and lateral stem make it look suitable for woodland spirits, the dryads of Greek mythology, to ride. I've found plenty of dryad's saddle in the woods, but I'm still looking for the nymph!

The entire mushroom smells like watermelon rind, something no other species (except for watermelons) can do.

Dryad's saddle grows on living and dead hardwoods, mostly in Eastern North America, but occasionally in the west. You can find it in the spring and fall, often year after year in the same location, recurring until it depletes its food source.

The mature mushroom is much too leathery and bitter to eat, but any part of the immature cap that you can cut with your fingernail is edible.