The McMinnville UFO photographs were taken on a farm near McMinnville, Oregon in 1950. The photos were reprinted in LIFE magazine and in newspapers across the nation, and are often considered to be among the most famous ever taken of a UFO.
Dr Bruce Maccabee Research discusses this in The Trent Farm Photos
It is also discussed and debunked by Robert Sheaffer here
Bruce Zybel has an article on it The McMinnville UFO Photos That Won’t Go Away
it is discussed in great detail in Above Top Secret
UFO evidence on the case