Where might I find a publically accessible, by purchase or free online, English translation of Olympe de Gouges' primary documents: Letter to the People or aka Project for a Patriotic Fund (1788); Patriotic Remarks (1789); and Declaration of the Rights of Woman and the Female Citizen (1791)?
The first stop when looking for primary source writing out of copyright is to go to the source or author's Wikipedia page and see if there's a link to it under External Links.
After that, searching archive.org and books.google.com are good choices before turning to Google itself.
Good luck!