I agree with brandnewday...ask him. No "special" cards. If you get a card, just a very simple one. They do not like to recognize their birthdays, etc. in the way that we use to.
He may want to celebrate his day in his own way w/o you being involved...to play it safe, just ask him. If he says he wants nothing in the way of celebration, please listen to him.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.