sorry most of these will be repeats
Miss Happiness and Miss Flower
Swallows and Amazons - except not S&A itself which is pretty dull IMO - start her on Winter Holiday, then Pigeon Post, then Picts and Martyrs, then maybe Great Northern, then the others. Oooh must reread.
I know lots of people who loved the Hobbit at that age. Not me - couldn't make head or tail of it.
THE RESCUERS - not the Disney version - loved all of those sooooooooooo much. Miss Bianca and the Salt Mine was my favourite of all but start her off at the beginning.
Joan Aiken - A Necklace of Raindrops and all her short stories, as well as Black Hearts in Battersea obviously.
Emil and the Detectives, although I think a lot of children do it in school now.
I loved Dr Dolittle at that sort of age, though they are some of the books I would never re-read now, and apparently they are pretty from a political point of view so I don't plan to introduce them to ds. Is that helpful??
NURSE MATILDA. Not the Nanny McPhee film novelisation.