Yes, CHESSES is a Scrabble word!

Letter values in Scrabble US: C 3, H 4, E 1, S 1, S 1, E 1, S 1.

Is it a valid word?

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

weedy annual native to Europe but widely distributed as a weed especially in wheat
a board game for two players who move their 16 pieces according to specific rules; the object is to checkmate the opponent's king

Also: bromus secalinus, chess game.