About 100 known species of truffle belong to the Tuber genus. Most valuable to gourmands are the French black (Tuber melanosporum) from the Périgord region, and the Italian white (Tuber magnatum) of the Piedmont district. Oregon has two whites, the Tuber oregonense and Tuber gibbosum, and the Oregon black (Leucangium carthusiana). The black has been called the most complex of any American truffle. It looks like a lump of dark coal, and is said to have aromas of pineapple, papaya, port, mushroom, chocolate, coconut, coffee, butter, pear, and even garlic-teriyaki beef jerky. And, I assume, male pigs as well.

In the mushroom industry, rival groups of pickers occasionally confront one another with guns and machetes, arguing over which shiitakes or morels belong to whom. Beyerle assures me this competition never happens with trufflers. Demand is not as high, and few people even know truffles exist there.

We stop at a grove of Douglas firs - a favorite host for truffles. Beyerle points to a smattering of squirrel middens, which indicates that a squirrel was recently up in the tree, eating a pinecone and dropping crumbs. Let's hope he also dropped something else. Unlike mushrooms, in which spores are scattered by the wind, truffles are self-contained, with spores inside. Spores are distributed when the truffle is eaten by an animal, passed through its digestive system, and eliminated, as Beyerle puts it, "packaged into a nice little fecal bullet." Not a phrase you'd ever see on a fancy restaurant menu. Regardless, whatever the squirrel has been up to here, it hasn't produced any truffles.

Beyerle and I meet up with the rest of our group, and it isn't looking good. Baskets are empty, faces neutral and unsmiling. The expedition trudges out of the forest, back to our vehicles.

SOME MOMENTS IN LIFE seem to unfold as if they were occurring for the very first time in history. Such as a group of people standing alongside a road in rural Oregon, eating sandwiches and having a detailed discussion about Italian truffle shavers. Someone unpacks a bag of chips and a container of sour cream-truffle dip. A pickup truck whizzes by. Does the driver have any idea?

I learn more truffle lore. Don't cook them, because the flavor escapes too much. Better to add them to milk-based ingredients, which capture and enhance the flavor. Homemade truffle butter is great over popcorn. Inserting thin slices under the skin of a chicken before marinating is also popular.

And then there's the issue of storage. A refrigerator is good, but the truffles' scent can permeate airtight containers, even eggshells. Beyerle says he had to get a separate minifridge just for truffles, and laughs. "My wife did not want truffle-flavored milk."

Truffles will keep for a month or so, adds Larry Schramm, another NATS member, but "they can go bad like that," he says, snapping his fingers. "They get slimy and smelly."

We talk about the truffle-as-aphrodisiac myth. Is it true? A big, bearlike man with a beard and wearing hiking boots, Schramm shrugs: "I've never had anybody tackle me on the street and demand sex."

A woman in our group mentions the Joel Palmer House, a local four-star restaurant that specializes in mushroom and truffle cuisine. Everyone perks up at the name. Jack Czarnecki is a legend among trufflers. Since 1997 he's operated his own restaurant in a renovated farmhouse, in the heart of Pinot Noir country in Dayton, Oregon. As far as truffle cuisine goes, he's the man. It's still daylight, so I get directions and head off.