Kenneth Grahame's The Wind in the Willows is a real classic of English literature.
I first read this book, when I was approximately 9-10 years old. I remember how much I liked it then. Although I'm older now, I still like it. I've read it a couple of times and I'll probably read it again soon.
Kenneth Grahame's writing is fluent and charming. He describes the life of the animals in an excellent way - it feels like they're alive. When you read the book, you come to care about the animals.
The Wind in the Willows is often categorized as children's literature, but in my opinion the true beauty and symbolism of this book opens only to adult readers.
Even if you don't normally read this kind of books, you should read The Wind in the Willows. Give it a chance and it will charm you.