Yes, CRESSES is a Scrabble word!

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

Is it a valid word?

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

any of various plants of the family Cruciferae with edible leaves that have a pungent taste
pungent leaves of any of numerous cruciferous herbs

Also: cress plant.