I mentioned this in an unrelated thread where @HappyOnion and I were going off the rails.
As a kid and even into my young adulthood, my maternal grandparents always called them mangoes. People who shopped their small grocery did too. Even stuffed baked bell peppers were called “stuffed mangoes”. When we visited my mother (who called them bell peppers at home in our state) called them mangoes there.
I tracked it down some years ago when it came up on CH. Going from memory, it seemed to exist in a fairly narrow horizontal band running at least from Ohio, through Indiana, Illinois, and Southern Iowa/Northern Missouri. Some references also claimed small parts of PA, KS, KY had the usage, but that it didn’t persist as long as in the other states. I heard it from old folks at least into the mid-1980s, but certainly no one in my generation around my parts (IL, IN) clung to it.
I’m pretty sure I did not have real mango until I was in my 20s, in the Army.