Yes, SARDINE is a Scrabble word!

Letter values in Scrabble US: S 1, A 1, R 1, D 2, I 1, N 1, E 1.

Is it a valid word?

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

small fatty fish usually canned
any of various small edible herring or related food fishes frequently canned
a deep orange-red variety of chalcedony
small fishes found in great schools along coasts of Europe; smaller and rounder than herring

Also: sardina pilchardus.