It seems like I know what this one is but I don't. What is it?

It's not pig weed is it?

Not pigweed but looks like another kind of Amaranthus

https://www.google.ca/search?q...

Yes, that must be it!! Thank you, Porkpal.

I was thinking not pigweed because the flowers aren't hanging

Hmmm. I was thinking Amaranthus retroflexus. But now wondering which pigweed it could be. I think I usually see this plant with the leaves full of holes from insects munching on them.

Maybe Amaranth palmeri? My plant is growing in mostly shade?

Palmer's Amaranth (Amaranthus palmeri)
http://www.eattheweeds.com/pal...

You don't think it is one of the green forms of Amaranthus caudatus?

I still vote for pigweed or possibly lambs quarters/goosefoot.

Well, it's growing in mostly shade at the edge of the back patio where the chickens like to go. Sometimes they deposit "stuff" which could extend the possibilities. Nearby-to the right is a wild currant tomato plant and something that looks like it might be some kind of sorghum.

Hmmm, now I'm not so sure. The growth pattern looks different from pigweed. Handsome chickens, though!