The main foods to stay away from are avacados, chocolate, coffee, anything with caffeine, and alcohol. I think ruhbarb and onions are bad for them too. I feed my Hahn's Macaw, Kiwi, fresh fruits in the mornings, like apples, blueberries, strawberries, oranges, mango, pomagranates (his favorite), and bananas. He also loves wheat toast and gets that every morning along with his fruit. Parrots also need fresh veggies, and I give Kiwi de-thawed frozen mixed veggies, and fresh steamed squash and zucchinni, mashed sweet potatoes, and he absolutely LOVES green bell peppers, yellow peppers and red peppers diced and mixed up. He also likes a little bit of tomato. Fully cooked beans are good for them too. I buy a 15 bean mix at the grocery store and make a little pot for Kiwi. I freeze what I wont use within a few days. Pasta is good for them and most birds love it, but I cant Kiwi to eat it.
They always need to have pellets available. I feed Kiwi Zupreem.
There are several pre-made cooking mixes on the market that you can buy for them that have grains, dehydrated veggies/fruits, nuts, and other good stuff in them. I think the best one is Beak Appetite. Most birds love warm food, and Beak Appetite has several flavors that smell wonderful.
My bird gets seed, but only a few times a week as a treat. Too much seed is bad for them. They also need nuts, but not excessive amounts.
There will be other people along with B&G's that can tell you more about what they feed, and have more info for you than I do. Good luck with your orphan!
Melinda