https://www.skyandtelescope.com/astr...snoopy-module/
Not well known is that Apollo 10 "snoopy" has been orbiting the earth for several decades. NASA never bothered to keep track of it, because it was just considered space junk after its usefulness was exhausted.
Earlier this year (2019), the British spotted it by accident and they now have a trackable orbit. Trackable, means that technically a capture and return could be possible, although expensive and risky (think 10x more difficult than rescuing something at the bottom of the ocean)
Only thing stopping anyone is: Should we?