Source for Farro
Farro is a wheat relative, Triticum dicoccum. Many sources find the more readily available spelt, Triticum spelta, an acceptable substitute, but it's somewhat mushier when cooked.
For farro, check Italian gourmet stores. I'd try Convito Italiano (Plaza del Lago, 1515 Sheridan Road, Wilmette, 847/251-3654); Isola Imports (1321 W. Grand Ave., Chicago, 312/421-9490); and Conte di Savoia (1483 W. Taylor St., Chicago, 312/666-3471). Spelt's available at most health-food stores.