I have a relative named Agnes in her early twenties. Don't do it. I find the Texas A&M jokes to be unbearable and I'm sure I hear less than 10% of what she hears
Mildred, Evelyn, Opal all names of my aunts +3 generations older than mine. Also try Betty as a diminutive for Elizabeth, Gerald, Hank, Errol, Mabel, Jerome, and Cordelia. These all scream white Midwestern US farmer to me.
Errol is most likely to have gotten into a bit of trouble and really seen the world when he was drafted for WWII.