Yes, SEAMEN is a Scrabble word!

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

Is it a valid word?

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

a man who serves as a sailor
muckraking United States journalist who exposed bad conditions in mental institutions (1867-1922)

Also: jack-tar, old salt, sea dog, elizabeth seaman, elizabeth cochrane seaman, nellie bly.