Yes, MILLET is a Scrabble word!

Letter values in Scrabble US: M 3, I 1, L 1, L 1, E 1, T 1.

Is it a valid word?

MILLET is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

any of various small-grained annual cereal and forage grasses of the genera Panicum, Echinochloa, Setaria, Sorghum, and Eleusine
French painter of rural scenes (1814-1875)
small seed of any of various annual cereal grasses especially Setaria italica

Also: jean francois millet.