Until recently, pecan truffles (Tuber lyonii) were considered a nuisance by pecan farmers. However, the pecan truffle has been gaining in popularity in recent years. They can now bring $160-$400 or more per pound.
The tuber body has a light brown outer skin (peridium) that may be rounded, lobed, furrowed or smooth. When mature truffles are cut in half, they have a marbled interior with white veins layered between brown veins where spores are produced. They're usually found in the top few inches of soil, sometimes poking up through the soil. If exposed, they become dried out or insect infested.
Where to find them
The range of the pecan truffle reaches from northern Mexico into Québec, Canada and from the eastern seaboard to the southern reaches of the Rocky Mountains. They are commonly found near Carya (hickory and pecans) and Quercus (oak). They have occasionally been found with Corylus, Castanea, (chestnuts) and Basswood trees. One productive habitat is well-managed pecan orchards, especially along the edge of herbicide strips. This is likely due to the raised pH of the soil.
Fruiting bodies are produced most prolifically on young trees which fruit toward the end of summer and into fall depending on the local climate. In the southernmost part of its range (Florida and southern Georgia), fruiting may continue through winter and as late as February. The fruiting bodies can reach up to 12 cm across at maturity; most are between 0.5 and 2 cm.
The pecan truffle comes from the same genus as, but is very different from, the famous white (Tuber magnatum) and black (Tuber melanosporum) truffles found mainly in Europe. Tuber lyonii is a white truffle but is a unique fungus having a unique flavor and texture which has become a favorite of chefs. Its association with the pecan trees found throughout the Deep South gives it special appeal.
There is great interest in the culinary world, and pecan truffles are currently harvested on a very limited basis. This cottage industry has a small but growing group of people harvesting truffles from local pecan orchards to market directly to individual restaurants. Prices are higher for truffles found with dogs because they're generally higher quality and have a stronger aroma. Using dogs is also a more sustainable method versus raking since only the mature truffles are harvested. There's a fledgling industry in Georgia that trains truffle dogs.
The problem is that they grow underground, attached to the roots of trees. To locate them, truffle hunters have traditionally used pigs because of their natural instinct for rooting. However, pigs have fallen out of favor and truffle dog use has greatly increased.
The pecan truffle is considered nonpoisonous. As with anything from the wild, always use caution when eating them. Specimens should be fresh and have a firm texture. Avoid older, darkened specimens, especially if they are softer than usual. Truffles from commercial pecan orchards could also have low levels of pesticide residue, although the small quantities consumed would reduce the potential risk.
There are other fungi that can be mistaken for truffles. Puffballs are the most common. Several things distinguish puffballs. They're usually uniformly round or pear-shaped and grow above ground. They are often white and have a sterile base or stalk. Puffballs are generally edible, except for the genus Scleroderma which is purple when cut open. Potentially, the most serious case of mistaken identity would be to consume a mushroom button, a small, unexpanded mushroom, from a highly poisonous genus such as Amanita. Slicing a mushroom button in half will reveal the stalk and cap instead of the uniformly marbled interior of a truffle. With any fungus, it's important to make a correct identification before consuming.
To serve, use a vegetable peeler to shave the truffles over eggs, risotto, sauces, potatoes or grits until you can smell the aroma. You might also like to try this recipe from the Atlanta Journal Constitution: Pecan Truffle, Shiitake and Ricotta Tartine.