C.M.
If she is breastfeeding, in addition to the gas-producing foods already mentioned, she should try eliminating other food groups to see if something isn't being tolerated. For me, it was dairy. Not only did my son feel better, but I felt better and haven't gone back to dairy since. When I weaned him onto couw's milk, he started getting ear infections, so he doesn't do dairy either. (He is 11 now.)
A friend of mine insists that I should try all-organic milk to see if it's the additives, not the dairy, that bothers us; I havent' tried that yet. Good luck.