Yes, DAHLIAS is a Scrabble word!

Letter values in Scrabble US: D 2, A 1, H 4, L 1, I 1, A 1, S 1.

Is it a valid word?

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

any of several plants of or developed from the species Dahlia pinnata having tuberous roots and showy rayed variously colored flower heads; native to the mountains of Mexico and Central America and Colombia

Also: dahlia pinnata.