I was able to visit the curatorial collection on a special tour several months ago, and got to see some very special treasures, including a Confederate Battle Flag used in Pickett's Charge (aka Longstreet's Assault). Of some items, the Park holds a multitude of, especially bullets (I remember a figure of at least 2,000 minie balls and etc.).
A pretty cool feature that the park has been doing recently is to record a short video called "Museum Mondays", where the park curator selects an item from the collection and explains a little bit about it. It has been going on now for several months, and I really dig it. The most recent edition is below (about a pocket revolver), but there are many more on the YouTube page, and older ones on the Park's Facebook page.