I hope someone here on GW knows the answer! I too have these plants (weeds?) and at first I let them grow, bloom and set seeds. The next year I had tons of them, so I immediately pulled started them all up. What is interesting is that the foliage looks like it belongs to the hibiscus family.

That's Velvetleaf, Abutilon theophrasti. Not native, but widely naturalized as a noxious weed. It's a big problem for farmers. You're right, it is a member of the mallow/hibiscus family.

Marty

The cotton farmers around here call it wild cotton,
it allways shows up in cotton fields.
Norm

What pictures?

I had three images in the original message. Here is a direct link to the first one. Hit "next" to see the other two.

Abutilon theophrasti

the dreaded Abutilon (sp?)

dont let those seed pods mature or you'll have quite a bit of weeding to do for the next few years.