Yes, SHITTIM is a Scrabble word!

Letter values in Scrabble US: S 1, H 4, I 1, T 1, T 1, I 1, M 3.

Is it a valid word?

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

shrubby thorny deciduous tree of southeastern United States with white flowers and small black drupaceous fruit
source of a wood mentioned frequently in the Bible; probably a species of genus Acacia

Also: southern buckthorn, mock orange, bumelia lycioides, shittah tree.