Hi Lauren!
First, a huge CONGRATS Mom! I can only imagine the joy your son will feel when he makes his first of likely many trips to
Disney World. I remember how special that moment was for both my children. My son's first trip was at 1 and a half. He doesn't remember it, but the hundreds of pictures we took captured the pure joy on his face when he was there. My daughter, however, took her first trip right before her 4th birthday. She is now in her teens, and STILL remembers much of her first Disney trip. The sheer beauty of capturing those Forever Memories..
In terms of receiving things, if you're staying at a
Disney Resort Hotel, sometimes if you give them enough head's up as to his birthday, there have been times upon checking in your room you'll find a small balloon with perhaps a short message wishing your son a "Happy Birthday." I should note that this is totally at the resort staff's discretion, so I can't make any promises, but sometimes they have been known to do a nice gesture such as this.
In other cases, at table service restaurants (again, totally at their discretion), if you mention that it is his birthday, they have occasionally brought one small cupcake with a candle on it as a small nod to him celebrating his birthday once you're wrapping up your meal.
Probably the most definite is getting a birthday pin or a "My First Disney Trip" pin from
Guest Services right after you enter the theme parks. This makes for a cool experience as Cast Members (and guests alike) instantly recognize the pin and will offer their "Happy Birthday's!" When my daughter was younger and wore the pin, she felt like a Disney Princess and it made her birthday fantastically more special.
Thanks for your question, and have a Magical Day!
Terry