Yes, ILEXES is a Scrabble word!

Letter values in Scrabble US: I 1, L 1, E 1, X 8, E 1, S 1.

Is it a valid word?

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

a large genus of dicotyledonous trees and shrubs of the family Aquifoliaceae that have small flowers and berries (including hollies)

Also: genus ilex.