Hello,
The vast majority of state flags are post-Civil War creations. Only Texas had an official state flag before the war.
The KY State Guard used a flag, based on the one example that survives, which was blue with a light blue center (circle) and within that center was the US coat of arms.
Buckner claimed to have designed the flag in 1909, and I think he is right based on other evidence I have found, and the KSG flag may well have been his inspiration.
greg Biggs