Green’s Dictionary of Slang

(US) used of anything pertaining to white, middle-class, mainstream styles: bland, unexciting, suburban.

1977		Rolling Stone 22 Sept. 46: Until rock ’n’ roll (and Elvis) came along, ‘popular music’ was 100% White Bread America.
1981		T. Wilkinson Down and Out 49: Normality was back in all its white-bread glory.
1988		NWA ‘Fuck Tha Police’ 🎵 A redneck, white bread, chicken-shit motherfucker.
1990		(con. c.1970) G. Hasford Phantom Blooper 23: Hey, man, don’t even talk to Black John Wayne about no Mickey Mouse listening posts and none of that other gung ho Audie Murphy whitebread shit.
1999		Indep. Mag. 20 Nov. 44: Consider the very American phrase: ‘He’s so damn white bread.’ Whereas in Britain, white bread has class connotations (tres proletaire), in the States the expression is used to denote a bland, white Anglo-Saxon Protestant kind of guy, who lives in a bland, dull, white Anglo-Saxon Protestant kind of suburb.
2000		Observer Rev. 26 Mar. 10: Music that carries all the insignias of white-bread suburbs.
2000		Gazette (Montreal) 17 Feb. 12/3: A ‘quiet, little, white-bread, podunk, white-trash, redneck town’.
2005		E. White My Lives 277: Perhaps because of his whitebread background, Stan was always susceptible to strong, satanic men.
2010		L. Redhead Thrill City [ebook] I wasn’t some white-bread, corn-fed, bible-studying yank goody-two-shoes with a dumb-arse name like Kimber.
2012		Slate 21 Nov. 🌐 White bread came to be associated with boring blandness, suburban sanitized white-picket-fence-ified phony gentility. A veritable curse upon a person or a work of art: ‘That's so white-bread’.
2015		S. King Finders Keepers (2016) 98: Just another whitebread high school kid from a so-so Midwestern school.
2018		Guardian CiF 31 Jan. 🌐 Go alone to events and places where most people are not white – not as a tourist but to break out of your limited whitebread world.
2020		D. Winslow ‘Sunset’ in Broken 190: [T]he famously buttoned-down, straitlaced, white-bread SDPD.