I usually will pull something if it's not something I purposely panted, but every once in a while I let one go to see what it creates. That happened a few months ago. I strated seeing the usual thistle weeds around the beds, but one of them really stood out, so I let it go. Here's what the leaves look like.
My thought is that maybe this is a giant sunflower- like a Maximillian variety. I had some of those seeds and planted them around and who knows if I was in a weird mood and planted some right here. That's the problem with seed insanity- you can't remember where you put them, you just want to GET THEM IN THE GROUND AND OUT OF MY SEED DRAWER, DAMMIT!
and it kept growing and growing- this is it on the right side. next to ANOTHER crazy big plant that I have no idea what it is.
Here's the other one up close and it doesn't look like a sunflower. In fact, there are two of these and the second one is branching out into 4 branches.