Green’s Dictionary of Slang

(US) of the country; rustic, slow, peasant-like.

1906		A. Adams ‘Around the Spade Wagon’ Cattle Brands 🌐 I squeezed the hand of an alfalfa widow during a waltz.
1913		J. London Valley of the Moon (1914) II 172: And what did the alfalfa judge hand’m? Fifty years.
1915		S. Ford Shorty McCabe on the Job 124: ‘Friends,’ says he, sweepin’ off the alfalfa lid with a flourish.
1930		J.P. McEvoy Hollywood Girl 31: The cute little baggage in ‘Get Your Girl’ and before that, in vode tab out in the alfalfa zone long enough to get herself kidnapped for a hat full of headlines.
1968		R.F. Adams Western Words (2nd edn) 5/1: alfalfa desperado A cowboy’s name for a hay hand.