Digital rendition of the Green Cross flag raised by Gregor MacGregor on Amelia Island, Florida in 1817, and later used as the supposed flag of Poyais in the 1820s.
Corroborated by description on page 127 of Owsley Jr, Frank Lawrence; Smith, Gene A (1997). Filibusters and Expansionists: Jeffersonian Manifest Destiny, 1800–1821 (First ed.). Tuscaloosa, Alabama: Alabama University Press. ISBN 978-0-8173-0880-3. "MacGregor's flag, a green St. George's Cross on a white background called the Green Cross of Florida, was raised over Fernandina on 28 June 1817."
Zscout370 at English Wikipedia