Green’s Dictionary of Slang

1. a clumsy oaf, a boor, a dull-witted peasant.

1918		Wadsworth Gas Attack 15: Clover Kicker’s Waltz.
1937		Literary Digest 10 Apr. 12: Clover kicker. Farmer, rube.
1968–9		in DARE.

2. a rustic, a farmer.

1916		Seattle Star (WA) 11 Nov. 8/3: ‘The gimp was doing the royal with some clover-kicker at the next board.’ [The boss was entertaining a friend from the country at the next table].
1920		N.Y. Tribune 9 Dec. 14/2: ‘Wild Bill’ Doig [...] the amibitious hay-shaker and clover-kicker had been fined $25.
1942		Berrey & Van den Bark Amer. Thes. Sl. §391.3: rustic, bumpkin, clover kicker.
1949		Monteleone Criminal Sl. (rev. edn).
1960, 1975		Wentworth & Flexner DAS.