Yes, SKIMMER is a Scrabble word!

Letter values in Scrabble US: S 1, K 5, I 1, M 3, M 3, E 1, R 1.

Is it a valid word?

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

a rapid superficial reader
a cooking utensil used to skim fat from the surface of liquids
a stiff hat made of straw with a flat crown
gull-like seabird that flies along the surface of the water with an elongated lower mandible immersed to skim out food

Also: panama hat, straw hat.