Yes, LEATHERLEAF is a Scrabble word!

Letter values in Scrabble US: L 1, E 1, A 1, T 1, H 4, E 1, R 1, L 1, E 1, A 1, F 4.

Is it a valid word?

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

stiff leathery-leaved fern of western North America having ovate fronds parted to the midrib
north temperate bog shrub with evergreen leathery leaves and small white cylindrical flowers

Also: leathery polypody, coast polypody, polypodium scouleri, chamaedaphne calyculata.