Yes, DAMASKS is a Scrabble word!

Letter values in Scrabble US: D 2, A 1, M 3, A 1, S 1, K 5, S 1.

Is it a valid word?

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

a table linen made from linen with a damask pattern
a fabric of linen or cotton or silk or wool with a reversible pattern woven into it