To start, definitely NOT avocado. Reportedly toxic to parrots.
For Bixby and Maya, here are the different fruits and veggies I provide: carrots, asparagus, bell peppers (red, yellow, orange and green), jalapeno peppers, Jamaican peppers, chili peppers, squash (butternut, green and yellow),pumpkin, blueberries, pomegranates, snap peas, broccoli, cactus pears, starfruit, bananas, grapes, kale, turnips, radishes, brown rice, quinoa, cucumbers, endive, dandelion, chopped celery, red swiss chard, granny smith apples, papaya, African horned melon, corn, hominy, chocho beans and garbanzo beans, as well as the aforementioned Volkman's Fancy Soak and Simmer for the majority of his legumes and grains.
Also some hard-boiled egg (with the crushed shell for calcium), though maybe once or twice a month. And assorted unsalted nuts for their treats.