crescione

Most often this means 'garden cress', though some Italians may use it for watercress, which is properly

crescione d'acqua or pepe d’acqua ('water pepper')

Other names you may see:

crescione inglese garden cress

crescione degli orti garden cress

Not too widespread outside the Romagna, where it's a common ingredient in salads, soups and piadina sandwiches