Welcome to the Moms Panel Ursula! We're glad you're hEAR!
Disney World is a great place to celebrate a 3rd birthday! I have a couple of suggestions for you.
My first recommendation is
Chef Mickey's at the Contemporary Resort. This location has a yummy a buffet and provides an excellent opportunity to dine with Mickey, Minnie, Pluto, Donald and Goofy. Its a convenient location if you're visiting the Magic Kingdom on the same day as your reservation.
I'd also suggest
The Crystal Palace located in the Magic Kingdom Your little guy will get a chance to meet Pooh, Eeyore, Tigger & Piglet. This location also has a yummy buffet.
I'd go ahead and make reservations as soon as possible. These are both popular dining locations and fill up fast. Call 407-WDW-DINE to make reservations.
Please let us know if you have any other questions during your planning. Its a pleasure to assist you!
Wishing you minnie magical memories :-) Allison