Yes, PIEDMONTS is a Scrabble word!

Letter values in Scrabble US: P 3, I 1, E 1, D 2, M 3, O 1, N 1, T 1, S 1.

Is it a valid word?

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

the plateau between the coastal plain and the Appalachian Mountains: parts of Virginia and North and South Carolina and Georgia and Alabama
a gentle slope leading from the base of a mountain to a region of flat land
the region of northwestern Italy; includes the Po valley

Not playable in Scrabble US: PIEMONTE.