Yes, CEREALS is a Scrabble word!

Letter values in Scrabble US: C 3, E 1, R 1, E 1, A 1, L 1, S 1.

Is it a valid word?

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

grass whose starchy grains are used as food: wheat; rice; rye; oats; maize; buckwheat; millet
foodstuff prepared from the starchy grains of cereal grasses
a breakfast food prepared from grain

Also: cereal grass, food grain.