That is a weedy abultion.

Yes, velvetleaf or Abutilon theophrasti. A common agricultural weed.

If you look at the floral structure it shows its mallow family affinity, different from that of squash family plants. Notice also the chambered fruits, quite unlike those of squashes, melons etc.

It's a weed. Make sure you get rid of it before the seed pots open.