The New York Times has published this amazing story written by James Barron; about the inverted Jenny Stamp, a batch of 100 stamps printed 100 years ago in 1918 featuring the Curtiss JN-4 plane known as “the Jenny”. What makes this batch special is that they have one small flaw, the Jenny is upside-down.

Inverted Jenny stamp

read more about the story of these rare and valuable stamps that have sold for up to 9.5 million dollars here:
https://www.nytimes.com/2018/09/06/nyregion/inverted-jenny-stamp.html