was wondering the best beans to use in therapeutic bags that you can heat &/or freeze that don't burn & smell
Any of them can burn. But I wouldn't use beans if you're planning to freeze.
You could always try buckwheat hulls (I can get them at the local HFS). But typically I just use rice. And expect the first half dozen times you use it it's going to be damp (you can minimize this by baking the rice on a sheet pan for a little while on a low heat).
Field corn is another one that I've seen used - not popcorn, but the type of corn that is ground up and fed to cattle (find it at a feed store).
But any of them will burn if you overheat them.