Hi William,
This varies from restaurant to restaurant.
Here is the best way to check each individual restaurant:-
1/ Visit the Walt Disney World website
2/ Click on WHERE TO EAT
3/ Click on Make Dining Reservations
4/ In the Enter a Restaurant Name box, enter the name of the restaurant which you would like to check (for example Tusker House Restaurant) & click Search for a Table.
When the search has been completed, you will be on
THIS page which as you can see, tells you that Breakfast is served from 8.00am - 10.55am, Lunch is served from 11.00am - 2.45pm and Dinner is served from 3.45pm - 7.00pm.
You can use this same method to check the times at any restaurant of your choice.
Wishing you a magical trip filled with memories which will last a lifetime!