Although frumento is properly 'wheat', gran or grano (grain) is commonly used as well, and the Italians, naturally, are great connoisseurs; see also grano duro and farina. There is a movement in recent years to bring back historic varieties of wheat and spelt (farro). Grano saraceno is buckwheat; grano di caffé is a coffee bean.
Some kinds of wheat grains you may see include:
Gran cotto (cooked wheat in a jar— used in the classic Neapolitan Easter pie, Pastiera)
Grani antichi: varieties of native wheat. Some 291 different ones exist (or existed) in Italy in the 1920s, including over 50 in Sicily (grani duri antichi siciliani) once the breadbasket of Rome.
Image by Meena Kadri