The Farmer and His Wife
(She can do more work in a day than he can do in seven!)

Then, there's always "The House Of The Rising Sun"

A couple of non-folk tunes:
Nine To Five
She Works Hard For The Money
Waitress In A Donut Shop (sung by Maria Muldaur)
(She Sold) Artificial Flowers
Abigail Beecher (My History Teacher)
Million-Dollar Baby (In the Five-And-Ten-Cent Store) [...she was selling china ...]
Jackaroe [she goes to war dressed as a man]
Ob-la-di (...Molly is a singer in the band...)

One other thought -- the song "Forty-Hour Week" mentions a lot of occupations, some of which (e.g.,"...the one who pours the coffee...") are usually/often women's jobs and others (e.g., "... the one who brings the mail...") which are not very much gender-associated. In fact, you could do a bit of a rewrite on "Forty-hour week" to tie it more closely to women workers.