The Green Children of Woolpit

It's often hard to do mysteries set in small villages hundreds of years ago, since they didn't keep a lot of records. There are actually two sources on this that date from not after the event. These two historians provide independent accounts of the green children of woolpit. The accounts are drawn from different sources, including eye witnesses. They are both from within a few decades of when the incident happened. So that's quite good sourcing for cident in a remote, mediaeval country village.