I received a paternity letter one time...turned out to be the most expensive gift i ever received ...lol
Your question is genuine in its' intent, but remiss of important details. Does he have a particular interest that could be enhanced by a certain gift? Do you have a large or small budget? What type of gifts have you gotten him in the past? Is he sentimental, or more practical?
I could go on, but you get the point. I am not sentimental, so cards, gifts etc, mean very little to me. A simple HFD is fine by me.
Perhaps if you asked your mother, she may have some ideas...she knows him best, no?
Anyway, I'm certain anything you get him will suit him just fine.:)
ct