What fruits, veggies, and grains should my young ringneck parrot eat?

Ringnecks should be fed a wide variety of foods. A high quality dry food mix that contains seeds, grains and nuts should be available at all times - a Small Hookbill or Cockatiel should be suitable for them. Clean, fresh water for drinking and bathing should also be provided.
Their diet should also include a good amount of leafy dark greens and vegetables (i.e. chard, kale, carrots, corn, celery, squash), as well as fruits (i.e., applies, grapes, pears, persimmons, pomegranates, figs, grapes, bananas).
Wild-picked green foods such as chickweed, seeding grass, dandelion (flowers, roots and leaves), shepherds-purse and sow-thistle make excellent additions to a healthy diet.

Germinated or sprouted seeds are especially important for the breeding season. They should be fed fresh making sure that it is not contaminated by bacteria or molt. It should have a sweet smell. If it smells foul or sour, discard. Frequent rinsing will help prevent spoilage. Sprouting: The Easy Way.

Calcium supplements, such as cuttlefish, shell grit, crushed oyster shell or calcium blocks should be available - particularly during the breeding season.
Millet spray makes a nutritious treat.