Oregon truffles are extremely rare and difficult to find, as both white and black Oregon truffles grow beneath the ground. It has been said that pigs can help harvest them by detecting the truffle aroma, but even if you have a proven technique they are still very hard to find. Because of the scarcity and desire for truffles, they tend to be expensive, and are sold by the ounce rather than the pound. Oregon white truffles can be harvested from November until March, while Oregon black truffles are only found December through February. WIKIPEDIA has everything you want to know about Truffles!