When Apollo 15 astronaut David Scott hopped across the lunar surface in 1971, he was carrying a pouch of tiny US flags in his spacesuit. The stash of flags was such a secret that Scott didn’t even know they were there at the time. Now one of the souvenir flags, the pouch, and the bracket where it was attached are up for auction. The flag is estimated to go for $15,000 and the bracket/pouch for $30,000, but I definitely think you need both lots. From Collect Space:

"This [hidden pouch] was apparently unknown to anybody else until the (Portable Life Support System’s Oxygen Purge System where the pouch was stowed were) disassembled after the mission by some other member of the CSD (Crew Systems Division) and the flag package was discovered," wrote Scott.

The identity of the original CSD member who hid the flags, or the person who found them afterward, is unknown…

Scott was presented with some of the flags and the 7.5 by 4 inch (19 by 10 cm) bracket as mementos of his flight by his management at the same meeting where he was told of their existence. A law passed in 2012 reaffirmed Apollo-era astronauts’ title to the items they retained as souvenirs of their missions…

The hidden flags were not the only secret souvenirs on the Apollo 15 mission. Scott and his two crew mates also took postmarked envelopes, a memorial statue, and timepieces that NASA later labeled as unauthorized. The hidden flags were not associated with those items, though.

An interesting read via Boing Boing