Yes, BIGAMIES is a Scrabble word!

Letter values in Scrabble US: B 3, I 1, G 2, A 1, M 3, I 1, E 1, S 1.

Is it a valid word?

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

having two spouses at the same time
the offense of marrying someone while you have a living spouse from whom no valid divorce has occurred