Not a plant I know in person, but check Virginia Buttonweed, Diodia virginiana.

Have you asked at the local office of your Mississippi State University Cooperative Extension Service?

kimmq is kimmsr

Yes I contacted someone on campus. A picture of the cross section of the stem is needed. I don't think I can get a picture that detailed of a close up of the stem with the equipment I have.

No office in your county? I have many times taken plant samples, in a sealable plastic bag, into the local office of the Michigan State University CES and if the horticulturist, or Master Gardener, there could not identify the plant it was sent to East Lansing. Working with pictures is not always a good method of identification.

kimmq is kimmsr

I see some round leaves which might be Dollarweed (Hydrocotyle). So does that mean this area is very moist?

Yes it is moist. There is plenty of dollar weed. I don't bother with weeds and the lawn thrives but this particular weed if spreading and snuffing out the lawn. I will try to take a sample to the local office.

Jean, I did get a clear photo doing as you described. I just don't feel it will expand and show enough detail for clear identification.