There's a book which was one of my favorites growing up (in fact, thank you, I need to find a copy of it to have now!) called "A Great Big Ugly Man Came Up And Tied His Horse To Me." It's not real poetry in the sense of deep metaphor, in fact it's more properly called verse than poetry, but it's absolutely wonderful. A seven year old will enjoy it, and I bet you will too! The title poem reads:
As I was standing in the street, as quiet as could be
A great big ugly man came up and tied his horse to me
That's the whole poem, and the book has a lot like that. I can't recommend it highly enough, if you like silliness (and if you didn't, you wouldn't be in R&S, would you?).