Fly Agaric: Amanita muscaria

Pileus
Cap 6-39 cm broad, rounded at first, then plane in age, surface viscid when moist; margin striate often with adhering partial veil fragments when young; cap red, usually with white warts but in one variety, yellow warts.

Lamellae
Gills adnexed to free, white to cream, edges roughened.

Stipe
Stipe white, 7-16 cm long, 2-3 cm thick, tapering to a bulbous base; partial veil membranous, breaking to form a superior skirt-like veil. Volva consisting of two to three concentric rings at the stipe base.

Spores
Spores 9-13 x 6.5-9.5 µm elliptical, smooth, nonamyloid. Spore print white.
Habitat
In the Bay Area, Amanita muscaria occurs under pines, especially Monterey and Bishop pine. Fruitings occur in early winter, and can be spectacular, with large groups or rings brightening the woods. The Fly Agaric shares the pine habitat with the much sought after King Bolete, Boletus edulis. Some mushroom hunters thus use Amanita muscaria as an indicator species.

Edibility
Toxic when raw. Contains ibotenic acid and muscimol. The toxins are water soluble. Many persons have eaten this fungus, without ill effect, after parboiling the sliced mushroom and discarding the liquid. For more edibility information, see Rubel & Arora, Economic Botany 62(3), 2008 (the printed article has a mistake...it states "250 g or 4 oz", which are not equivalent, correction from Arora):
"Cut the A. muscaria cap and stalk into thin slices (no more than 3-4 mm or 1/8" thick) to hasten dissolving of the active constituents. For each 110 g or 4 oz of mushroom, use 1 liter or quart of water with 1 teaspoon salt. Garlic and bay leaf can be added to the water for flavoring. Bring the water to a rolling boil, then add the sliced mushrooms. Begin timing the cooking once the water returns to a boil. Boil for 10-15 minutes, until the mushroom is soft, then drain and rinse."

Comments
With its bright red, sometimes dinner plate-sized caps, Amanita muscaria is one of the most striking of all mushrooms. The white warts that adorn the cap, white gills, well developed ring and distinctive volva of concentric rings separate the Fly Agaric from all other red mushrooms. There are several color varieties of A. muscaria in the U.S. ranging from red to orange, yellow and white, but only two occur commonly in the Bay Area, Amanita muscaria var. muscaria with a red cap and white warts, and A. muscaria var. flavivolvata, with a red cap and yellowish warts. Photo at top is variety flavivolvata.