Truffles, singular τρούφα.
The ancient Greeks, including Aristotle, knew them and called them Hydnon (one of the popular names these days for them is Hydanon, showing an impressively long memory). Most truffle finds were accidental, dug up as people looked for other mushrooms, but starting in 2007, Greeks began taking truffle hunting seriously, notably in Western Macedonia and around Meteora. They acquired trained truffle hounds and know-how from the Italians, and business is booming. Along with the famous black truffles (tuber melanosporum), Greece also has plenty of the prized white Alba truffles tuber magnatum pico and now exports them to the USA.
Image by Morgan McBain