With autumn slowly fading to shorter days and colder evenings, the elements have conspired to provide a bountiful harvest of mushrooms this season, and foragers have been furtively gathering them all across West Marin.

Mushrooms have been sprouting heavily in recent weeks among the leaves and needles that have fallen in showers, about the stumps and roots of oaks and pines, and everywhere dead and decaying matter feeds new life.

Foragers have been finding mushrooms everywhere they grow and eating them however they can. They have been gathering varieties of wild mushrooms by the basketful, unloading them in bulk upon kitchen counters, cooking them in stuffing and in soups.

At Manka's Inverness Lodge, the menu this week has featured mushroom soup and mushroom risotto, mushrooms wrapped in kale and savoy, sautˇed mushrooms with garlic custard, and mushrooms served with candied pecans.

"It's been a great year for them," said Manka's owner Margaret Grade. "We just use them like crazy. We don't have any problem having them on the menu in four different ways."

Most plentiful this year are the chanterelles, an orange colored fungus shaped like a trumpet or vase that usually grows among the roots of oak trees and conifers.

"It's been good for chanterelles. They're growing like weeds," said Andrew Romanoff, an Inverness forager who eats his chanterelles in a sauce served over noodles.

A versatile mushroom with a meaty texture, chanterelles are a rather common species but still a delicacy. Margaret Grade said she will pay her local foragers the seasonal rate of $8 to $10 per pound for fresh chanterelles, but will often just barter a meal for them.

Grade added that chanterelles cook well in goat-cheese omelets and in chestnut stuffing. "They're just the most wonderful thing," she said.

However, Romanoff lamented the season hasn't been as auspicious for boletes, a spongy group of fungi including the Porcini and Moretti mushrooms prized by so many Italian immigrants. "They'll be coming along because of the good rains," Romanoff said optimistically.

But in truth, no one can say for certain when a mushroom will bloom, how abundantly it may appear, or how long the season may last, said Bob Harris of Inverness, an erstwhile mushroom salesman with a degree in mycology, the study of fungi.

"Every species is different," Harris said, explaining that each variety of mushroom has evolved to grow upon a particular host, either living off decomposing matter or exchanging nutrients with living roots.

Both chanterelles and boletes bloom out of an underground layer of the mushroom called the mycelium, a network of small threads that spreads through the soil. The part of the mushroom that appears above ground is the equivalent of a plant's flower or a tree's fruit.

Harris said it takes just the right combination of mist and fog, rainfall and temperate weather to get the mycelium to grow, and it may take an entirely different combination to persuade the mushrooms to bloom.

The mushroom season truly began somewhere around late August, he said, when the fog dampened the ground just enough to awaken the underground mycelium. "If you don't have a good growth before the flowering, you won't have a good season," Harris explained.

No evidence of the mycelium's growth appeared until sometime in October, when most of the mushroom varieties started appearing in large quantities, he said, noting there was a three-week window in October when the boletes were flowering.

"There's no way to say exactly why they grow," conceded Romanoff, the Inverness boletivore. "There is no rhyme or reason."

The number of mushroom species growing in West Marin is also a complete mystery. Harris told The Light he once spotted nearly 30 varieties of edible mushrooms in a season. A county naturalist, Bob Stewart, said he has seen about 100 different species in a single hike.

The most notorious mushroom growing locally is the Death Cap mushroom, Amanita phalloides, which has poisoned a number of people in the Bay Area over the years. Eating two ounces of the Death Cap is more than enough to completely destroy an adult's liver and kidneys, causing a slow and agonizing death.

Other mushrooms may be poisonous to lesser degrees, causing nausea, cramps, vomiting, or hallucinations. Harris urges amateur foragers to join the San Francisco Mycological Society and learn to distinguish poisonous species from edible ones.

"The dangers are extreme," he said. "This is something you must learn."

Still, many foragers are content to rely upon the knowledge that has been passed through generations. Romanoff said he learned to forage for mushrooms as a child in England and gathers only the few varieties he is certain about. Grade said many of her foragers grew up in the area and simply know the woods.

But foraging has been discouraged on most public lands in Marin County. It is prohibited in county open space, state parks, and the Golden Gate National Recreation Area. At the Point Reyes National Seashore, visitors are permitted to take one quart of mushrooms a day.

If any of these regulations are being violated, the foragers aren't speaking. Few would ever consider divulging the spots where they know certain mushrooms grow. Mushrooms that flower from mycelium will appear in the same spot over and over again, noted Harris.

"Many of the fungi grow on the same tree," he said. "Once you know the location, it's a matter of beating somebody there."

Romanoff said foragers guard their secrets carefully because they know they must compete with everyone from voracious deer to renowned chefs for a few choice mushrooms. "It's a passion," he said. "It's a love. I know people who have slept in their trucks to be the first one out."

He insisted that anyone can find good mushrooms, and suggested a variety of general locations to look. "You can go to Limantour. You can go down to Bolinas. You can go to San Rafael, and in the middle of town you can find them...

"You can go to Petaluma, drive around those wonderful houses, and they'll be growing right under the trees in the lawn."