Yes, BOXBERRIES is a Scrabble word!

Letter values in Scrabble US: B 3, O 1, X 8, B 3, E 1, R 1, R 1, I 1, E 1, S 1.

Is it a valid word?

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

creeping woody plant of eastern North America with shiny evergreen leaves and scarlet berries
spicy red berrylike fruit; source of wintergreen oil

Also: mitchella repens.

Not playable in Scrabble US: SPICEBERRY.