Yes, CALABASH is a Scrabble word!

Letter values in Scrabble US: C 3, A 1, L 1, A 1, B 3, A 1, S 1, H 4.

Is it a valid word?

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

round gourd of the calabash tree
tropical American evergreen that produces large round gourds
Old World climbing plant with hard-shelled bottle-shaped gourds as fruits
bottle made from the dried shell of a bottle gourd
a pipe for smoking; has a curved stem and a large bowl made from a calabash gourd

Also: calabash tree, crescentia cujete, bottle gourd, lagenaria siceraria, calabash pipe.