You did so well with the acacia, maybe you can ID this one too. I thought this was the same as the acacia but I dug it out today, and it's definitely not the same. I never saw any blooms, so they are either not on top like the acacia or mimosa pudica, or they are really small. The seed pods aren't flat like the acacia, but rounder like a green bean. I thought it was a vine, but it's not. It just has a reclining habit, and that is what makes it hard to find in taller flowers like obedient plant. By the time I see it, it's already 2 feet long. The stem branches just under ground so what looks like a clump of 3 or 4 separate plants is actually the stems of 1 plant. That's probably why it won't pull out of the ground, even after a rain. It just breaks off where the stem comes out of the ground. From that underground branch, the root goes straight down 3-6 inches and then branches again into multiple roots. It has no thorns and the leaves don't close when touched.

This is one growing through my neighbor's fence - shows how it grows along the ground.

This may be the flower.

I broke this one in the usual place at the bottom of the stem, and then again where it branched underground and the place where the roots branched off. The roots break easily and that makes it hard to get it all out.

This is the worst weed I've ever tried to get rid of. I'll take nutsedge and dandelions over this any day. I thought it was a vine or spreading by underground runners and was sticking the ends into a bottle with a heavy concentration of Roundup. I've done that for several years and it kept spreading. The Roundup would kill the part in the bottle but not the roots so I decided to dig it out. I'm sure there are lots of roots left so I'll have to do it again and again until I get rid of it. I can't dig out the one in the fence because the root part is on the neighbor's side of the fence.

There has GOT to be a way to get rid of this.