Not clover, this is Oxalis, O.drummondii or similar.

What color flowers does it get?

Not that it matters. You just need to keep after it. St Aug will choke out grassy weeds but it cannot win against broadleafed weeds.

Do you have any pictures of the dollarweed. There are a lot of plants that go by that popular name.

Thanks for the help, everyone. It does appear to be some type of oxalis, although I have never seen it produce any flowers.

I have enclosed an additional collection of photos. The top two pictures are of the oxalis, and the bottom two are what I have been labelling "dollarweed". As you can see, it has the same affect of "choking out" the St. Augustine.

{{gwi:79232}}

It appears that pre-emergents are the best chemical strategy for oxalis. Any recommendations?

Thanks again for your assistance.

do a soil test and add lime. Will take a while but oxalis does not like limey soil.

You don't see flowers because you keep them mowed along with your grass. This particular group of oxalis (maybe O. intermedia, a common weed in the South), grows from small bulbs in the ground. Pre-emergents would not be what I would use for most efficient control. I'd get after it with spot treatments of a post emergent, checking the label carefully to make sure the product is listed as safe for St. Augustine.

Whatever you do, don't apply that lime unless a soil test clearly indicated that you need to change the pH of your soil.