Mystery Plant

Hello Bloggerettes! You know how they say if you plant it, water it, and it dies, it's a plant? Pull it out, and it grows back, it's a weed? Well, I am just stumped as to what this plant could be. It started with hearty green leaves, and hubby said what is it, did you plant it? No, I didn't plant it, let's just see what it does. Some have said it's a weed. Hummm, don't think so. The stem is hearty and thick. I have also had someone tell me, that it's a poisonous Caster Bean tree. WHAT??? They are native to Africa! Where would that come from?? Then, I thought perhaps some type of squash, as neighbors have grown them. No little flowers or buds. So far just leaves, and some of the lower leaves have little squiggly white lines going through them. It is growing rapidly, and didn't seem to mind the hot, humid days we have had. Does anyone know what it could be? I had thought perhaps a sunflower? We will just have to wait and see!

Debbie