What would be an appropriate item for a Medal of Honor recipient to autograph?

Let’s say I had the rare opportunity to meet a recipient of the Congressional Medal of Honor and I really wanted to get their autograph.

First of all, would this be considered disrespectful in any way, even if they were okay with it?

Secondly, what would be an appropriate item to have them autograph? A unit patch? A plain index card? A book? Does it even matter?

Thanks in advance,

Fiddlebastard.