So how does one pronounce ma'am? Like ham or like palm?
The Internet offers contradicting opinions...thus I post here....
I can't speak for any others but as a northern Englishman when I address my mother I call her mam, which rhymes with ham. However were I ever to encounter Brenda, then I would address her as ma'am, which rhymes with palm.

A lot of it is to do with where you're from and so depends on your accent.