Yes, KAPOKS is a Scrabble word!

Letter values in Scrabble US: K 5, A 1, P 3, O 1, K 5, S 1.

Is it a valid word?

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

a plant fiber from the kapok tree; used for stuffing and insulation
massive tropical tree with deep ridges on its massive trunk and bearing large pods of seeds covered with silky floss; source of the silky kapok fiber

Also: silk cotton, vegetable silk, ceiba tree, silk-cotton tree, white silk-cotton tree, bombay ceiba, god tree, ceiba pentandra.