Yes, GINGKO is a Scrabble word!

Letter values in Scrabble US: G 2, I 1, N 1, G 2, K 5, O 1.

Is it a valid word?

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

deciduous dioecious Chinese tree having fan-shaped leaves and fleshy yellow seeds; exists almost exclusively in cultivation especially as an ornamental street tree

Also: maidenhair tree, ginkgo biloba.