Yes, DONKEYS is a Scrabble word!

Letter values in Scrabble US: D 2, O 1, N 1, K 5, E 1, Y 4, S 1.

Is it a valid word?

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

the symbol of the Democratic Party; introduced in cartoons by Thomas Nast in 1874
domestic beast of burden descended from the African wild ass; patient but stubborn

Also: domestic ass, equus asinus.