Greater New Orleans is zone 9. These five do well in fall.
Louisiana iris
A native. Purple, blue, yellow, or white. It likes moisture, but the bed still needs to drain.
Gulf Coast muhly grass
Pink plumes in fall. Full sun and soil that drains.
Mexican bush sage
Purple flowers and gray leaves. Sun and drainage. Bees and hummingbirds use it.
Beautyberry
Purple berries in fall. Birds eat them.
Japanese maple
Red and orange leaves in fall. Give it part shade and soil that drains. Afternoon sun here can scorch the leaves.
Want them planted? Call 504-975-6291.