Apparently there are about 25-30 different plant called mallow. So I can't be certain that we'd be talking about the same plant. Even in the UK there Lavatera and Malva ssp all referred to as Mallow.
However, most mallows seem to be edible - roots were originallly used as the basis for marshmallows (I'm guessing they weren't big pink fluffy things then
). Shoots and young leaves can be eaten raw or cooked and the seed head are supposed to taste like peanuts. They also produce a mucilage in their stems which are good for digestive disorders and for rubbing on bites and stings. It also helps thicken soups etc when cooked.
All of that, of course, depends on you identifying the species etc and checking it out, but all in all they're a pretty useful plant.
I've eaten the flowers and small leaves in salads. We used to grow a small white-flowered variety - can't remember the proper name, sorry. Very pretty. I don't remember it being particularly tasty though - it was some years back.