Yes, truffles are mushrooms; that is, they are the fruiting body of a fungus. The word "truffle", in the broad sense, is applied to any lumpy fungus that fruits underground and is not internally differentiated other than in texture. In this sense, they can be found almost anywhere - - for example, acorn truffles, which mimic the acorns that squirrels bury, and seem to rely on the squirrels' digging them up for dispersal, or deer truffles.
But if you want the famous eating truffles, you will have to go to Europe or Oregon. Oregon is the only place that the "good eating" truffles are known to occur in the wild in this country, though I've heard that people have been successful in cultivating truffles here by bringing inoculated trees over from Europe and waiting for them to grow. This seems to take 17+ years. I've also heard once that another truffle has been discovered in Georgia, but I haven't heard any more about it.
