Yes, DERRISES is a Scrabble word!

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

Is it a valid word?

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

any of various usually woody vines of the genus Derris of tropical Asia whose roots yield the insecticide rotenone; several are sources of native fish and arrow poisons