Different individual birds will have different likes and dislikes. You will have to experiment with a variety of food items. Most natural foods can be fed to your birds. Be sure to feed only the amount of fresh food that will be consumed before it spoils. Remove any that they do not eat.
Egg shells are a good source of calcium.
When you have eggs for breakfast, rinse the shells and microwave them for four minutes to kill salmonella, etc. Put them in your bird cage and the birds will go wild for them. You should also supply cuttlebone for your birds. This can be purchased at the pet store. It is a white and about 2x5 inches.