George Washington lived much before the invention of photography and his face is only known through paintings. However, John Quincy Adams was photographed by Philip Haas, a few years after he left office.
Andrew Jackson was next and his picture was taken several times including the following daguerreotype, of 1845, a few months before his death:
Interestignly, it seems that Barack Obama was the very first President of the United States to replace the formal painted portrait with a (digital) photography.
According to the Metropolitan Museum of Art web site, John Q Adams’ image is a copy of a lost daguerreotype of Adams taken by Philip Haas in 1843.