I don't know what it is. But I can tell you what it isn't.
This doesn't appear to be any US city, state, governor, nor county flag.
However, those lists are not exhaustive. Check the flags of local government.
It's not likely a historical Confederate States of America (CSA) flag, CSA flags usually, but not always, have three stripes. It could be a modern amalgamation.
Nine stars brings to mind the flags of the early US confederacy, but they only had three stripes and the stars were in a ring.
CSS Curlew used nine stars in a grid as their naval ensign, but again, only three stripes.
Here is a 9-star, 9-stripe United Confederate Veterans flag.
rareflags.com's FAQ offers a few theories.
There’s never been a time where nine stripes and thirteen stars would have been official, yet often on antique pieces of folk art and artwork, especially very small pieces, the creator might omit stars simply out of necessity due to lack of space. I’ve seen this often on small maritime paintings where the artist was unable to put the full complement of stars on a ship’s flag. Ship flags from the 19th century, and up until the early 20th century, also known as ensigns, commonly featured cantons of 13 stars. This was so that the canton was more recognizable at long distances. Most likely, on the carved ship you describe, the maker attempted to approximate a 13 star ensign. There are printed parade flags that date from the Civil War and Centennial Era that also feature less than 13 stars. Those that surface typically feature star counts of 7, 8 or 9 stars. While some collectors believe that these are prototype confederate flags, or confederate sympathizer flags, they are typically very small and while it may be plausible that they were made by southern sympathizers, I personally believe that the makers of these flags simply opted to print fewer stars to make them look bolder rather than printing the full complement of 13 stars, which might not look as striking.
Despite being marked by the seller as a CSA flag, I feel this teeny little 9-star (circular formation, one in the center) 13-stripe flag matches that description.