Looks more like a Goldenrod, Solidago to me. July is too early for most Goldenrod to bloom.

I've never seen a Goldenrod six feet tall where I live in the upper South, but there is a variety call "Giant Goldenrod\" that does get 4'-7' tall.

We have wild goldenrod all around the state roads here, but they're usually more in the 2' tall range so that's what threw me off. And I'm at least 10 miles from them, so that's a bit far for a wild seed. I've never seen a Giant out there, though, so that seed would have had some travelling to do!

A drop-off by a bird isn't impossible, of course, but it seems like an unlikely position considering it's right in line with where I always plant shorter annuals.

I planted Love Lies Bleeding amaranth* in the back of this garden a few years ago, so when this started to get tall I thought maybe it was a lingering seed from one of those. But they were a lot bushier than this is.

* https://www.gardeningknowhow.com/ornamental/flowers/love-lies-bleeding/love-lies-bleeding-flower.htm

Amaranth was supposed to be a prolific self seeder, but none ever came back so that was pretty disappointing :-/

Goldenrod is usually treated like a weed in my area, but if that's what it turns out to be then I think I'll split it up and replant it in the back of the garden for next year. It's a cheap (read: free) background for my gardens that attracts good pollinators, and it's not too much work to keep it in control.

Solidago canadensis has no trouble reaching 6' at bloom height. That could very well be what it is. There are so many species of Goldenrod pinning the species down may be tough.

Do be aware that some solidago (and whatever they've been taxonomically split into) can be prolific spreaders in good soil. Nothing too rambunctious, but they DO spread.

@fig_insanity Z7b E TN, thanks for the warning! Luckily I have 9 (10?) full sun gardens now, so it wouldn't be too much of an issue to dig up babies and find them a new place.

Until I get overwhelmed, of course. That's what's happened with Mondo grass, Autumn Joy sedum, and irises... I kept dividing and dividing, until I just don't have anywhere else to put them! I give away a ton of them every year, but still end up tossing 90% of them.

If it does turn out to be goldenrod, I wish it was a shorter variety. I'm limited with options on 6' tall monsters!