Jimmy Carter reported a UFO sighting in 1969.
Only President to ever report something that dumb.
In 1952 the U.S. Airforce reported that 3 Unidentified Flying Objects were seen flying over the White House on September 11, 1948. That's a strange one.
Jimmy Carter saw Venus (I'm not making it up).
The very well documented sights in Washington, DC, which nearly caused a panic, were caused by a temperature inversion and reflected lights. While there are currently unexplainable sightings, neither of these are.
I've seen many strange things in the sky (including a U-2), I've never seen anything unidentifed.