Green’s Dictionary of Slang

alvin n.

[a ‘typically’ rural name]

(US) a yokel, an unsophisticated dweller in a small-town or rural settlement.

1950

Goldin et al. DAUL 18/1: Alvin. (West) Farmer; hick. ‘Yeah, some alvin beefed on (complained about) us to the town clown (constable).’.