Yes, CRACKER is a Scrabble word!

Letter values in Scrabble US: C 3, R 1, A 1, C 3, K 5, E 1, R 1.

Is it a valid word?

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

a thin crisp wafer made of flour and water with or without leavening and shortening; unsweetened or semisweet
a poor White person in the southern United States
a programmer who cracks (gains unauthorized access to) computers, typically to do malicious things
firework consisting of a small explosive charge and fuse in a heavy paper casing
a party favor consisting of a paper roll (usually containing candy or a small favor) that pops when pulled at both ends

Also: cracker bonbon.