No, this isn't a Fear Factor stunt. People are shelling out top dollar (really!) to indulge in these Pacific Northwest truffles.

It's a warm morning in the rolling hills 45 minutes west of Portland, Oregon. Our hunting party fans out into the forest, armed with baskets and gardening rakes. The mood is as intense as if we were on an ­African safari, except our goal is a wild hypogeous fungus - better known as the coveted truffle.

Representing the height of culinary decadence, truffles are also known as fairy apples, black diamonds, and black pearls. For centuries, they have been said to possess mystical aphrodisiac powers. And while truffles grow around the world - with French and Italian varieties in particular costing around $2,000 a pound - according to many palates (including the late James Beard), Pacific Northwest truffles taste as good as the European ones. And at just $300 a pound, they're proving increasingly popular with Americans and our shrinking overseas dollars.

Even better, the truffles are free this morning, as part of the monthly foray of the North American Truffling Society. Whatever­ we find, we get to keep. Based in nearby Corvallis, the NATS group claims a few hundred amateurs and professionals, including some of the best-known authorities on truffles and fungi. About 10 have shown up, mostly age 50 and over - an earthy, good-humored crowd.

Truffles grow underground, so we look for signs of animal activity, where critters have dug holes to find and eat truffles. Voles, mice, squirrels, bear, deer, and elk all love the fungi. "They know right where they are, they can smell 'em," says Adrian Beyerle.

Beyerle works with the Oregon State University Mycological Collection in Corvallis, part of an herbarium that houses the world's most complete collection of hypogeous fungi. People mail truffle samples to OSU, where the truffles are then identified from the OSU database. "We find new species on a regular basis," says Beyerle. "There's really no end to the research."

Beyerle knows his stuff, so I stick close, asking him obvious questions like, How come we're not using pigs like they do in Europe? Beyerle tells me that when a truffle matures, it produces a chemical similar to a sex pheromone found in male boar saliva, and this chemical attracts sows. If a female pig finds a truffle, she'll eat it immediately, unless you stop her. And if the sow is full-grown and hungry, this will be a brief and fruitless struggle. So, no pigs today.

At the base of a 20-foot tree, Beyerle points out some white mycelium - white, wispy, goopy stuff that signals the beginning stages of truffle growth. According to Beyerle, the forest was sprayed with mycelium a few years ago in an attempt to accelerate the process. Truffle cultivation is in its infancy, however, and nearly all the world's truffles are still gathered in the wild.

As Beyerle pokes his rake about the ground, he explains that truffles grow attached to tree roots, because as they give the tree minerals and water, the tree feeds back sugars so the mycelium can bear fruit. He then tells me he's found up to 16 truffles in one day. We scratch through the moist soil. Lots of mycelium, but no truffles.