WASHINGTON — The old American tradition of keeping souvenirs as historical mementos is the focus of a new exhibit at the Smithsonian Institution.

The National Museum of American History has opened the new exhibit, "Souvenir Nation," at the Smithsonian Castle. Some items on view date back to times when souvenirs were taken, not purchased.

It includes a brick from President George Washington's childhood home, a fragment of Plymouth Rock chiseled off by a 19th century tourist, pieces of the Berlin Wall and even locks of hair from former U.S. presidents.

Curator William Bird Jr. wrote the new book, "Souvenir Nation," to accompany the exhibit and showcase some of the Smithsonian's most eccentric artifacts.

The history museum is currently renovating its west exhibition wing. This exhibit will be on view through August 2014.