Yes, BOYSENBERRY is a Scrabble word!

Letter values in Scrabble US: B 3, O 1, Y 4, S 1, E 1, N 1, B 3, E 1, R 1, R 1, Y 4.

Is it a valid word?

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

cultivated hybrid bramble of California having large dark wine-red fruit with a flavor resembling raspberries
large raspberry-flavored fruit; cross between blackberries and raspberries

Also: boysenberry bush.