Weird plant-thingy growing amongst my rhubarb?

Pigweed 100%. Amaranth family, technically edible but I'm not a fan personally. I'd take it out before it goes to seed because those things produce a shit ton and you'll be ripping them out for years after.

https://cals.cornell.edu/weed-science/weed-identification/pigweed-identification/how-identify-pigweeds

Looks like something in the mint/sage family Lamiaceae with the square stems, parallel leaves, and the look of that flower bud.

I am way off. That's an amaranth/spinach family now that I have my glasses on. I think that's Amaranthus retroflexus or common amaranth. It is a weed, so rip it!

Seek by I naturalist is an app you can point your camera at and it tells you what the species is

Seeds are edible. You can rip it out while still green and shake the seeds out after it has dried. Superfood for free.

A close-up

Thanks a lot for the answers everyone 💪