Yes, TEFFS is a Scrabble word!

Letter values in Scrabble US: T 1, E 1, F 4, F 4, S 1.

Is it a valid word?

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

an African grass economically important as a cereal grass (yielding white flour of good quality) as well as for forage and hay

Also: teff grass, eragrostis tef, eragrostic abyssinica.