@Petebacher, when I first started on the forum I found this thread to very educational on native plums and selected varieties. Many of the best ones would be best sourced from members on the forum, as they might be willing to dig root suckers and provide them to you. I’ve recently been able to go that route and received 3 small plum trees.
There are many other plum threads that might be helpful, I would suggest using the word “Chickasaw” or maybe “native” in your search string.
In my research I determined that these plum varieties (not all native) sounded the most like winners for where I live: Toole’s Heirloom, Guthrie, Odom, McKibben, Marianna (when pollinized by native hog plum), Excelsior, followed by Robusto and Munson.