SAN FRANCISCO - Restaurants pay top dollar for prized winter truffles - the fleshy fungi delicacy that grows from a symbiotic relationship with tree roots - from Italy and France.

They were on display one recent weekend at Oenotri, an Italian restaurant in downtown Napa, Calif. There, a waitress carefully pulled the truffles from a small brown box and weighed them on a scale. An exotic food luxury comes at a price: The tiny fist-sized truffles were worth $4,000.

While U.S. chefs buy most of their truffles from the famed food regions of Provence in France and Tuscany in Italy, there is a truffle movement afoot in America, with growers from North Carolina to California to Oregon hoping to cash in on the highly prized underground fungus.

One of those people is Robert Chang of the American Truffle Co., which sells its intellectual know-how to would-be truffle growers.

The San Francisco Bay Area company has financial stakes in truffle orchards in 15 countries. In the United States, Chang is making his pitch to vineyard owners, among others.

"There is a healthy level of interest" among California grape growers, Chang said in an interview.

One of those is Northern California vintner Robert Sinskey.

With the help of American Truffle Co., Sinskey recently planted 563 truffle-inoculated trees on a little more than an acre of land in the Carneros region, an area that straddles Sonoma and Napa counties at the north end of the San Francisco Bay and is renowned for producing quality Pinot Noir and Chardonnay grapes.

Sinskey, who grows grapes on 200 acres in Napa and Sonoma using biodynamic farming methods, said he turned to truffles as a way to complement his agricultural techniques and to pair with his wines. His wife, Maria, is an accomplished chef who prepares food at their winery.

Trees are "the most natural way" to provide shade for sheep that graze on the land and truffles are "a great use of the land" that "dovetails nicely with our concept of perfect-circle farming," said Sinskey, who hopes to collect his first batch of truffles by 2015.

Per acre, a truffle-producing orchard has the potential to generate returns of seven to 10 times that of a vineyard, according to American Truffle's marketing materials, which state that a truffle farm is much less labor- intensive than a vineyard.

Chang said it costs around $100,000 to start up a five-acre truffle farm. Costs include the trees and irrigation equipment. His company typically uses English oak or hazelnut trees.

A former engineer, Chang got hooked on truffles while living in Europe. He recently hosted the first-ever Napa Truffle Festival. The Napa fete joined the ranks of U.S. truffle festivals.

The Oregon Truffle Festival is approaching its sixth year with its Jan. 28-30 event in Eugene, Ore. Ticket prices range from $100 to $1,000 depending on the food session or forum, and many are already sold out.

The 3rd Annual National Truffle Fest will be held in Asheville, N.C., from March 3 to 6. Tickets cost $500 for the full weekend of events.

Truffles have been in culinary use since Greek and Roman times and are among the world's most expensive foods. Depending on the quality or the year, truffles can cost from $300 to $1,500 per pound on the market.

The French black and Italian white truffles are the most highly coveted. Known as "black gold" or "white gold," both are sold from December through March. The French Burgundy is a less-expensive summer truffle

Due to the unstable global economy, prices for Italian white truffles - sold in the winter and dubbed "white gold" - have been weak, according to a recent Bloomberg News report.

As of April 2009, there were 300 acres of truffle orchards planted in the United States, but, according to a feasibility study conducted by Oregon State University scientists, few have reached maturity.