Okay, well, I've definitely done the Multiple-food-allergic-toddler, supermodified class.
Since most "celiac" foods and dietary advice eliminates wheat relatives in FAVOR of rice, that is no doubt why you are feeling considerable angst on that score.
Quinoa. Your new bestest friend in the world. Seriously. High in protein, unrelated to pretty much every other food, cereal, grain, seed out there... and it makes a pretty tasty rice and pasta substitute.
Oh-- and there are corn-quinoa pastas, too. My daughter virtually
lived on those when she was tiny.
Other starches that are still okay:
potatoes, corn, millet, buckwheat (it isn't really wheat or even related).
Just because I'm curious, does your child have
reaction history to all of those foods? That is, how did you find out that he was allergic to bananas, rice, and apples? The reason that I ask is that some allergists encourage parents to eliminate foods on the basis of testing-- without really considering (I think, anyway) just how difficult they are making things. Seriously. "Oh, it's no big deal... just eliminate soy, wheat, milk, eggs, and oh yeah-- rice and all fresh fruit, too."
Ohhhh... is THAT all... ANYway. If those are things you're avoiding because of TEST results, I'd insist on some clarification from the allergist. A few people
are actually allergic to apples and rice, certainly-- but they are VERY uncommon food allergens. VERY. Rice is a real stinker to get rid of if you must avoid wheat.