they look like laid down stands of crab grass or maybe nimbleweed. Nimbleweed will usually branch out like that and have the smaller root balls but it is hard to tell when dead
https://www.amerigreenonline.com/weed-identification this might help
You could put down a grabgrass preventer and overseed what whatever grass you want to keep the weeds down.
Dethatch what you have now - either with a harrow or lawn dethatcher, a rake if you have neither. Then aerate before putting down the new seed. If you are in northern missouri dont put down the crab grass preventer until late april/early may....earlier further south you are. Don't use a weed and feed as it might kickoff FA in the pond. Some folks use corn gluten as a natural crab grass preventer
