According to news reports, President Obama gave Lily Ledbetter the pen with which he signed the bill named after her.
If she or her heirs should decide to sell that pen on eBay, how could they prove the provenance? Photos of the event won’t show enough detail to identify the pen. Do recipients of such presidential mementos receive any kind of documentation?
Well, as far as value goes, it’s what you can make the buyer believe. I’m sure this pen probably came with a copy of the bill, some personal correspondence and a photo. From my watching lots of Antiques Roadshow, it seems like if you have a “package” like that, and especially if there was press coverage of the event, you have enough evidence to prove the item valuable. I doubt there is anything to keep you from swapping out an identical pen. But obviously you couldn’t sell it again.