I came across an article on the last great American treasure this week, the Forrest Fenn Treasure Chest. As a child, I loved researching for lost cities (Cortez), anything related to the Ark of the Covenant, and Confederate troves of gold. I haven’t really thought about these Indiana Jones type of quests for years. Most of these were featured on Unsolved Mysteries. There are many to choose from, some are probably hoaxes:
Forrest Again (More detailed article)
Still, these are fun to read about. So, choose your own adventure. And remember, you can find anything on the internet.