I have a lot of it this time of year, too. Don't know any good way to get rid of it. I don't know what Weed-B-Gon is, but if it isn't specifically a broad leaf weed killer, you might try one.

BTW, you have some chickweed coming up in it. You can put that in salads, it's edible.

I finally gave up and called a company to come treat the lawn. Once I can get a handle on it, I'm going to take over and try organic... but for now I'm too overrun and overwhelmed to do it myself.
Weed B Gon is a broadleaf weed killer... and it works... sort of. It makes the weeds yellow and wilt, some of them dying completely. Others, like Oxalis, seem to recover just fine afterward. Groan!