Here are few mentions of Frank L. Foster:

1910 Green Co., Ky. Miracode census index
Willie L Foster; ED: 0039; W; 28; Ky; Visit: 0033; Green, Summersville; Relation: Husband; Relatives: Wife Allis 26, Ky Dau Sallie F 06, Illinois Dau Lena A 05, Illinois Son Frank L NR, Ky

Cemeteries of Green Co. Ky. Vol. 1, by Froggett and Houk, p. 6
Bennett Cem.; located near Gabe.
Willie S. Foster 19 Oct 1882 - 19 May 1945
Ollie G. 5 Feb 1884 - 27 Sept 1970
Frank L. Foster 1908 - 1973
Nella K. Foster 1910 - (married 6 Feb 1928)

Kentucky Death Index, rootsweb
FOSTER FRANK L; age 64; death place GREEN; residence GREEN; death place 19 Sept 1973

SSDI
FRANK FOSTER; B: 14 Oct 1908; D: Sep 1973; last residence 42743 (Greensburg, Green, KY); SS# 400-20-8071; Issued in Ky.