Proso millet (Panicum miliaceum) is a fast-growing annual cereal grass valued for its tiny, round, husked grains — the classic "millet" of birdseed mixes and, across much of Eurasia, a human staple. The cleaned kernels are pale yellow to cream, scarcely larger than a mustard seed, with a mild, faintly sweet, gently nutty taste, and the grain is naturally gluten-free.