California's cannabis producers are not seeing the windfalls predicted, amid regulations and a robust black market that are cutting into legal pot profits. Sharyn Alfonsi reports. A letter written by Christopher Columbus, describing his discovery of the Americas, became the world's first best seller more than 500 years ago. As Jon Wetheim reports, the surviving copies are so rare and valuable, they're being stolen and replaced with forgeries. And Ethiopian pilgrims have been trekking to this mysterious holy site for centuries. Scott Pelley has the story on this week's "60 Minutes."