Green’s Dictionary of Slang

gobbler’s knob n.

also gobbler hill

(US) a generic nickname for anywhere considered far away.

[US] ‘Miscellany’ AS X 80/1: With its hills, hollows, and swamps, southeast Missouri is well adapted to propagation of the Podunk idea. . . Emerging from Nigger-Wood Swamp, one is likely to find himself in the vicinity of Gobbler’s Knob.
[US] in DARE.