Dear Conway Co., AR, Thank you for contacting Extension with your Natural Resource questions. I hate to be the bearer of bad news, but I do not know what plant it is. I've asked our agents and looked through my books, but I am not sure what it is called. However, one of our pasture agents says GrazonNext HL Herbicide, will take care of your problem. I do not believe it is a non-native invasive. I looked through UGA's website, www.invasive.org, and could not find it.
My recommendation is to pull up one of the plants and take it to your local Extension office. If the local office cannot figure out the plant, they will ask one of the Forage Specialist in Fayetteville for final ID. I trust this helps. - Andy