Stephen,
Are you looking for seeds (pecans) or seedlings? If you are looking to plant your own seed stock to graft to later, one can walk the public spaces (forests, streams, parks, courthouse
lawn (?) ) and find
native stock. Once these are a year or two old, then the graft
wood can be attached. I have a few good sources here in Texas for seedlings, but shipping may not be ideal. There are other good sources closer to you. You may want to contact folks on this list and discuss your needs and/or concerns with chemicals.
https://www.georgiapecan.org/pecan-tree-nurseries.da
If this is a DYI project to ensure purity of
root stock, I would find an area of undeveloped riparian area or wood lot that matches your soil type. Spend some time walking looking for native
trees that thrive in that soil. Harvest all the nuts you can and start them in a prepared bed to graft later. This was my plan; but to keep my ag exempt status, I need to place the trees much sooner than I can grow them. So I am working with one of the companies on that list to get a combination of root stock and grafted starts.
Always open to discussion on pecans as that is my focus right now. Care to share your project?