It’s a weed. Doveweed as some others have said. Check out the link below from the University of Florida. It will provide you with good info.

Doveweed - University of Florida, Institute of Food and Agricultural Sciences

This one of the many reasons I mow my own yard. I still get weeds coming in from the 3 adjacent properties but I watch it closely and handle any weed “invasion” as I find it. I’m a little OCD on this subject 😎

What ever it is called, It does like wet moist ground. I have a septic system and does like that area. It will kinda die back over the winter months but it will come back and the mid summer is when you will notice it the most. It probably came to your yard from your mower guys. The Pre Emergent comment you received it spot on. Round up now sells weed killer that is made to put on St Augustine Grass and will NOT kill the grass only the weed. You may want to give it a try. Good Luck

Crabgrass killer. Won’t kill St Aug. but will turn it a little white for a week or so.
Manufactured by Syngenta, Tenacity is one of the safest and most effective weedkillers on the market. It targets and effectively kills weeds like crabgrass, nutsedge, dandelions, clover, and others, either before they sprout (pre-emergent control) or after you notice patches of weeds on your lawn (post-emergent).

It's a weed/grass like St. Augustine. Terrible! It will take over your lawn and you won't like it. Spectracide makes a Weed Killer that also kills Nutsledge and Crabgrass. Home Depot sells it. Mix with water in a spray container. Very affective. Better hurry! Go online to see if they have it in stock or order online and pick n it up at Home Depot.

The weed/grass is easily pulled out, roots and all. Do it before it spreads.

So sorry that I cannot help you with your question but I do have a sort of related comment. I could never understand why fake grass wasn’t permitted in TV. It seemed to make sense to me…no watering or mowing, always green. So what’s the issue as long as it can drain when it rains? That is UNTIL I visited a friend in Indian Harbour Beach this weekend. A house on their block had it and some beautiful palms, but it looked to fake. I was awful. Now I completely understand.

Any garden idea, it is a good idea to see what they look like in real life. They all look great in the ads.

A weed is by definition any plant that you don't want there. Seeds are everywhere.
Plants wanted and not, want to spread. Some are eaten by birds and travel great distances. Where we used to live, dandelions were everywhere. As a kid I used to enjoy blowing the seed balls. Was it my fault? Perhaps many of them.
My grandmother thought they were pretty. Perhaps, smarter than we were.
Temperature? I have plenty of other weeds but no dandelions.

Our neighborhood used to have loads of thistles, which seemed to shoot up out of the lawns overnight, but I have seen none for several years.

You are quite right! I did the same thing as a child with the dandelion seed heads. In one of my grade school classes we learned that the leaves of dandelion are edible so we ate a dandelion salad in class!
Hated having them in my yard as an adult though.

The Picture This App cost $30 per year, if you feel it's worth it.

Dandelion weed is also a great addition to salads, and can be sauteed in olive oil and sprinkled with lemon juice for a tasty side-dish.

You can also get the LENS app if you have an Android phone. It's free and some phones come with it already loaded in.

In the Northeast, Bermuda IS a weed. No one up north puts down Bermuda on purpose. It's invasive and will destroy a bluegrass/rye lawn in a single season.