Quinoa (pronounced: ki:nwa) is not a true grain. It is instead closely related to beets, spinach, and tumbleweeds.
Quinoa arose in the Andes. It was domesticated 4,000 years ago, after a few thousand years of being used for pastoral herding. Someone figured that what was good for the alpacas might be good eating.
Quinoa has a complete protein content, and is high in protein, iron, magnesium, and phosphorus, as well as offering a goodly portion of calcium.