Yes, POTATOES is a Scrabble word!

Letter values in Scrabble US: P 3, O 1, T 1, A 1, T 1, O 1, E 1, S 1.

Is it a valid word?

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

an edible tuber native to South America; a staple food of Ireland
annual native to South America having underground stolons bearing edible starchy tubers; widely cultivated as a garden vegetable; vines are poisonous

Also: white potato, irish potato, white potato vine, solanum tuberosum.