My girls used to love a handful or 2 of corn once a day, then DP brought home some live mealworms and crickets, they went mad for them!
I got a bag of dried mealworms for them which they love and now they're not fussed about boring old corn. 
Dried meal worms are expensive...
They like fruit and veg but in more of a casual way.
Does anyone's feathered friends have a particular delicacy they go mad for or does anyone know where I can get the worms cheaper in bulk?