It probably can't quite compete with all the memories they have of landing on the moon, but the second best souvenir the Apollo 11 astronauts have of their adventure has to be this solid gold model of the Lunar Module given to them by Cartier on their return.
According to Cool Hunting; Michael Collins, Buzz Aldrin, and Neil Armstrong traveled to Paris as part of many celebrations held in their honor, where they were presented with these intricate—and incredibly valuable—models to commemorate their achievement. And buried inside each lander was a small piece of microfilm from the French paper Le Figaro listing the names of people who donated money to have their names included. Weird.
Today two of the gold models remain in private collections, but the third is back in Cartier's possession and will actually be on display at The Forbes Galleries in New York City starting on March 16 as part of its "Out of this World! Jewelry in the Space Age" exhibition. They might not get you to the moon, but they'll certainly send you over it. [Cool Hunting]