Farro is an ancient grain. In fact, it's the oldest grain there is and it is believed that all other grains derive from it. It was a daily staple in the diets of Ancient Romans, as well as people in the Mediteranean and the Near East. However because it's difficult to grow and is a low yielding crop, it nearly became extinct. Nowadays it is grown mostly Mugello region of Tuscany. It is currently becoming more popular with the health conscious as well as in upscale restaurants. It's quite high in protein, fiber, B complex vitamins and is very low in glutten, which is good for people with glutten allergies.
Similar to spelt, wheatberries and barley, farro has a nutty flavor and a chewy texture. It's great in soups since it doesn't get mushy even if it's over-cooked and it's excellent on its own as the base of a salad or a side dish. Its unique texture makes it a nice conrast for virtually any vegetable, nut, or dried fruit. Try it tossed with chopped tomatoes and kalamata olives, a handful of fresh herbs, and drizzled with olive oil and red wine or balsamic vinegar. Combine it with toasted pine nuts and currents or grilled eggplant or roasted squash.
Farro may be a bit difficult to track down, but a good place to start is any healthfood store or well-stocked Italian markets.