For the series of articles Cain did for Mencken and The Mercury in the 1920s, see 60 Years of Journalism by James M. Cain, which I edited for the Popular Press (1985).
“Pastorale” is included in The Baby in the Icebox and Other Short Fiction by James M. Cain, Holt, Rinehart and Winston, 1981; Penguin, 1984.