The Winter Oyster, Pleurotus ostreatus, is our most frequently encountered edible mushroom. That fact along with its health benefits and ease of identifying make it the one mushroom everyone should learn.
It's more tan and typically has a less-pronounced stem than its cousin the Summer Oyster. It grows in shelf-like clusters on wood fall through spring. The cap grows up to 15 cm wide, becoming flat and somewhat depressed toward the center. The gills (frequently inhabited by black beetles) are fairly close and run down the stalk (when there is one). The stalk is typically off-center. The spore print is white, gray, or lilac. Its smell--somewhat fishy--is its key identifying characteristic. I harvested these after a substantial rain, so the smell was not very pronounced.
I recommend dry sautéing since they are often water-logged.