Yes, MUSKMELONS is a Scrabble word!

Letter values in Scrabble US: M 3, U 1, S 1, K 5, M 3, E 1, L 1, O 1, N 1, S 1.

Is it a valid word?

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

any of several varieties of vine whose fruit has a netted rind and edible flesh and a musky smell
the fruit of a muskmelon vine; any of several sweet melons related to cucumbers

Also: sweet melon, sweet melon vine, cucumis melo.