Its clover! Red clover Trifolium pratense. It's a European species that is widely naturalized in N. America and used as a pasture/forage crop for livestock and used to make medicinal teas and stuff (I think). I have never found it to be terribly aggressive and pollinators seem to like it quite a bit so I personally don't go out of my way to get of it when I find it. But they can get sort of big and "weedy looking."

Thanks Zach! Looked that up, and that sure is it. I read up on it, too, and some of the medicinal properties are interesting such as reducing cholesterol, and preventing osteoporosis! I probably won't use it, or enough of it, to help with that - but interesting info :) I think I'll keep it, but I'll move it to another garden bed that is more on the "natural" side (that means I don't do a whole lot with it and just let things do their own thing, lol). Not sure it will like the transplanting, but we'll see. It does look a little weedy and spindly where it is, but was thinking that's because it's growing underneath some other plants. But that may just be way it normally looks - if so, then may end up pulling it out.

Yup, red clover! I had some show up in my yard last year and this season it grew larger and made a whole bunch of blooms that the pollinators LOVE. Growing up as a kid with a flower child momma in the 70s, we drank a lot of herbal tea made from the stuff and it's really quite nice. I also remember plucking the blossoms and sucking on them -- tastes sorta like Japanese honeysuckle.

I've also got a lot of white sweet clover I've allowed to overseason (I initially thought it was alfalfa) and now it's about to bloom, just as the red clover is starting to fade. Several clouded sulfur butterflies have been laying eggs on them. We used to have so many of the little yellow things flitting about in the alfalfa fields here in Northern Colorado; they seem to have become more and more scarce as years go by.

The other clover in the yard is Black Medic, which I keep mostly in check but allow in a few bare spots where nothing else will grow. Tiny pollinators really like it and it's helping to fix nitrogen in the long run.

Does anyone remember when lawn mixes had Dutch white clover in them?