In a stretch of high-grown Tuscan woodlands, a man and his dog pace through the dappled shade of poplars and oaks, casting about and sniffing, until the small sable mutt begins to scrape away the rain-softened earth with his snout. “Ivan, easy now!” says the man, Daniele Borgogni. He gently tugs Ivan away from the hole in the soil, pulls a brush-tipped spade from his belt, and unearths the delicate buried treasure: a truffle about half as long as his hand. 

“From the moment a dog starts digging, you’re holding your breath until you see the truffle,” Borgogni says, reaching into the dirt and pulling up a twisted and unmistakably pungent tuberous mass. He offers Ivan a biscuit and smells the truffle with his eyes closed. In the past, Borgogni has lucked upon a truffle bigger th...