sort of looks like a sunflower to me.

Mia, When I read your plant description before I reached the photos, I was picturing velvetleaf (which sometimes is misidentified as sunflower until it blooms). From the photo posted, I'd say it likely is a sunflower. Depending on the variety, you can get the reddish or purplish stems like that on a sunflower plant that is mostly green otherwise. A bird likely planted it for you. We do feed the birds and they tend to plant sunflowers all over the place for us. We also have native sunflowers that pop up all over the place. At this time of the year I find myself yanking out oodles of sunflower seedlings that are popping up in places where I don't want them.

Dawn

Thanks, Moni and Dawn! I haven't planted full-size sunflowers since I was a kid so didn't recognize it. I guess it won't hurt to have it in the tomato row if I leave it there.

Mia, You're welcome.

I used to grow tons of sunflowers right in my garden. They are so beautiful and I love them all. However......they also attract some insects, like stink bugs, that are hard to control and can wreck a garden. Stink bugs and leaf-footed bugs are my worst tomato pests, so I wouldn't grow anything near the tomatoes that would attract them.

I no longer grow sunflowers within the fenced garden where I grow tomatoes, but I'll grow them in a different garden plot---like having all the tomatoes in the front garden and the sunflowers in the back garden.

One way to use sunflowers is as a trap crop away from the garden to attract the pests that like them away from your actual garden to a different area. That is how I use them now, having learned a few years back that I had a lot less stink bugs in the garden if I grew the sunflowers as far away from it as possible.

Dawn

Here is a link that might be useful: Trap Crops for Stink Bugs/Leaf-footed Bugs