The Reagan Presidential Library in Simi Valley (near Los Angeles) has a copy of the Magna Carta, on loan from Lincoln Cathedral, on exhibit from January 23 to June 20, 2009. I've read that this is one of only four copies in existence, and that only one copy travels out of England. The document from 1215 is part of the library's newest special exhibit - Magna Carta: The Essence of Democracy.
I plan to go see this exhibit. If there's anyone who would like to go along, pm me. Even though I live nearby, I've never been to the Reagan Library. Maybe I thought since I always voted against Reagan, they would charge me extra

But the two presidential libraries that I have visited were both facinating, and well worthwhile. So I'm looking forward to this!