Present for older sibling

Crystal • High school sweethearts who never fell out of love.
My obgyn mentioned something to me a few weeks ago and It just came back into mind. She had asked me if I planned on getting our son a gift from the baby. I looked at her confused since I personally have never heard of this. She explained it briefly but I'm at a loss at what to give him! My husband mentioned a book as he loves books. 
Did you gift something saying it was from the baby to your older children? If so, what? 
He's so excited for her I'm sure he just wants her here now lol