You may also want to check out these picture books that celebrate the power of imagination:
My Garden by Kevin Henkes. A small girl enjoys weeding and watering in her mother's garden, but she can't help imagining what her ideal garden would be like. Jellybeans would grow on bushes and the air would be full of birds and butterflies. Henkes' pastel-hued, blue-outlined illustrations make the improbable seem plausible.
Jeremy draws a monster by Peter McCarty. Stay-at-home Jeremy spends his days drawing. When he creates a very large blue monster (who comes to life), he is taken aback by its neverending demands, starting with "Draw me a sandwich. I'm hungry!" Jeremy must be very clever to get rid of the monster for good.
Big Plans by Bob Shea. We first meet our narrator seated in the corner of his classroom, saying "SOON... the entire world will know of my big plans." (If you read the writing on the blackboard, you may get an inkling why he was sent there, i.e. "What I say does not go.") Not satisfied with dominating the business world, the brash young fellow even imagines that the U.S. President steps aside due to the force of his ambitious personality.