Yes, MALLETS is a Scrabble word!

Letter values in Scrabble US: M 3, A 1, L 1, L 1, E 1, T 1, S 1.

Is it a valid word?

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

a sports implement with a long handle and a head like a hammer; used in sports (polo or croquet) to hit a ball
a light drumstick with a rounded head that is used to strike such percussion instruments as chimes, kettledrums, marimbas, glockenspiels, etc.
a tool resembling a hammer but with a large head (usually wooden); used to drive wedges or ram down paving stones or for crushing or beating or flattening or smoothing