Yes, CINQUEFOIL is a Scrabble word!

Letter values in Scrabble US: C 3, I 1, N 1, Q 10, U 1, E 1, F 4, O 1, I 1, L 1.

Is it a valid word?

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

any of a numerous plants grown for their five-petaled flowers; abundant in temperate regions; alleged to have medicinal properties
an ornamental carving consisting of five arcs arranged in a circle

Also: five-finger.