This was apparently bird or wind planted. I planted peppers (chile pequin) and initially treated it as a pepper seedling, pinching to promote bushiness. After some time I realized that it wasn't a pepper but wanted to see what it would grow into. When it began setting white flower buds, I thought it was an Ageratina havanensis which I do have in the yard. The white buds started turning purple so I thought maybe Conoclinium which I also have. It doesn't appear to be either.

Overall height is around 4 feet with a 2.5 feet width at the top. I live near Fort Worth, Texas if that is important.

Thanks in advance for any ID help. I'll be collecting seeds because I've never seen bees loving on a flower like this!

Please excuse the rose that needs deadheading. I'll get to that soon!