When you say she can’t eat wheat, do you mean that she has Coeliac disease? Has she been tested and diagnosed by a Dr or is it a self diagnosis? The only reason I mention it is that if she has a true wheat (gluten) intolerance she’s going to need to be really strict with her diet. Even contamination from food prepared on the same surface as bread etc could present a problem. If it’s gluten (which is in wheat and lots of other things) that’s the problem then it could be hidden in lots of things (lots of prepared sauces, beer, lager, lots of prepared meals etc). The biggest problem with Coeliac disease is that if you don’t adhere to the diet, you may not have symptoms but it massively increases your risk of gut malignancy – this risk is normalised by following a strict gluten free diet.
Anyway, back on topic – she could have rice, potatoes, fruits, veg. You can make gluten free bread (if you’re diagnosed with coeliac disease you can even have it free on prescription) using gluten free flour, but don’t share a breadmaker with ordinary flour otherwise it will be contaminated.
Beware of cereals – most will either contain wheat or will have been exposed to contamination with wheat during manufacture. Some people with gluten intolerance can have oats.
I would urge her to get properly diagnosed if not already done so and if she has been properly diagnosed, she’d have access to a dietician and membership of coeliac UK who would provide her with much more info than you would ever get on here (no disrespect to any contributors). DON’T go to a health food shop for diagnosis. It’ll either be wrong or she’ll be told that she has a yeast problem or a lactose intolerance (nobody ever comes away being told they’re normal).
It’s said that Coeliac disease is massively underdiagnosed in the UK (incidence varies from country to country) – current estimates are that around 1 in 90 people have it, many have no symptoms, those that do are mostly “vague” symptoms, but if a proper diet isn’t achieved then they run a really high risk of malignancy and a thing called lymphoma, which you don’t want, trust me.
Oh and if you don’t have wheat in your diet already but you’ve not been properly tested, you’ve got to reintroduce wheat into your diet for the tests to work.