She opted for an Oscar de la Renta floral gown for a White House state dinner last year honoring Germany (Rihanna wore a version of the same gown to the 2011 Brit Awards).
Traditional mementos, such as a red-sequined ball gown from a state dinner and scribbled-on speech cards, also are on display.
Diana famously wore the deep navy, figure-hugging velvet gown to a gala dinner hosted by President Ronald Reagan, during her and Prince Charles' first joint state visit to the U.S. in 1985.