Truffles are a fungus that grow underground. They can be hard to find, so people use pigs or trained dogs to find them.
Some people pay large sums of money to be able to eat them.
The most expensive Truffles are White Truffles from Alba, in Italy.
The most expensive truffle ever sold weighed 1.5 kilograms and cost $330,000!
(You'd have to really love mushrooms to buy that!)