Yes, SALMAGUNDIS is a Scrabble word!

Letter values in Scrabble US: S 1, A 1, L 1, M 3, A 1, G 2, U 1, N 1, D 2, I 1, S 1.

Is it a valid word?

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

a collection containing a variety of sorts of things
cooked meats and eggs and vegetables usually arranged in rows around the plate and dressed with a salad dressing

Also: mixed bag.