Hi Yolanda,
Congratulations on your daughter's accomplishment and celebration at Walt Disney World!
There are a number of restaurants at Magic Kingdom on or near Main Street, but the only one that is a buffet is
Crystal Palace. It is a beautiful space and serves buffet breakfast, lunch and dinner. Guests are joined by Winnie the Pooh and friends.
I've always enjoyed both the food and the atmosphere here and I think you will find it a great celebration meal. I suggest you make reservations as soon as possible because it is a popular location.
Other table service restaurants along Main Street include:
In the New Fantasyland, you also may want to check out Be Our Guest inside the Beast's Castle. The decor is stunning, and the food is great. Reservations are accepted at dinner and are very popular. But the restaurant is quick service at lunch (no reservation required).
I hope that helps. Please let me know if I can answer any other questions for you. Enjoy your celebration with your daughter!
Wilma