Wheatgrass is a nutrient-packed member of the cereal grass family, which includes rye, barley and oats. Wheatgrass powder is made by freeze-drying (see above), oven-drying or air-drying fresh wheatgrass. Believed to have originated in ancient Egypt, wheatgrass was brought to America in the 1930’s but was not widely used, it has become a more popular supplement in recent years.