A forest truffle is actually a mushroom, but an unusual one—it grows underground. Obviously, that means they're especially difficult to find since you can't see them. That's why high-quality truffles in Italy and France are often worth hundreds of dollars—they're culinary treasures. These mushrooms exist in the US, too, and they're almost as good as those from Europe. While truffles are one of the world's most expensive ingredients, they can be found for free if you know where to look.
How to Look for Truffles
Rely on the help of forest critters.
Voles, squirrels, and chipmunks love truffles just as much as humans do, and if you look for evidence that they've been digging in a certain area, you just might find truffles nearby. Like other mushrooms, truffles often grow in clusters quite close to one another—so if you find one, you may find more in the near vicinity.
Search near trees.
Truffles are always found near a tree's roots. Specific types of truffles have affinities for certain forest trees, but almost any tree can support them—especially Douglas firs, pines, and hemlocks. However, you aren't likely to find them under maples and cedars.
Probe for truffles with your bare hand.
When you find evidence that animals have disturbed the forest floor (small areas of pushed-up earth and small holes in the duff), push your hand under the surrounding duff and, with your fingertips, feel around for a hard, ball-shaped object, generally the size of a walnut or a ping-pong ball. There may be only one or there may be several. When you're done, pull the cover of duff back into place to leave the area like you found it.
How to Know You've Got a Truffle
When you've found what you think is a truffle, sniff it. If it has a rich, earthy, garlicky, pungent smell (some think the aroma is wonderful, others think it's funky), it's ripe and eatable. You may not smell anything right away; often, conditions in the woods are cold and wet during truffle season, and the truffle may need to warm up before it gives off its scent. Take it home and smell it again. If there's still not much fragrance, wrap it in a paper towel and put it in the fridge for a week or so to ripen. (However, if it's been harvested too young, it won't get any riper.) Another way to determine if you have a real truffle is to cut it in half; most eatable truffles have solid cores with unique, beautiful marbling throughout.
Train Your Dog to Hunt for Truffles
Use the truffle you've found—especially if it's pungent—to train your dog to find more. Place the truffle in the toe of an old cotton sock, along with some other stuffing. Use it to play "hide-and-seek" with your dog. Make sure you reinforce the scent by letting the dog smell the sock between each search. Use a command like "Get the truffle!" each time. Remember to reward with food and praise for each success, and make the search harder and harder, always using the command "Get the truffle!" Eventually, you can move the game outside, where you can bury the sock in the ground or under pine needles. Keep the sock in the fridge; eventually it'll get very ripe, but your dog will love the smell. Once your dog gets good at this game, take him out to the woods for the real thing. A good truffle dog is the answer to consistently finding plenty of ripe truffles.