Sugarlump and the Unicorn by Julia Donaldson (3+)

Follow the adventures of Sugarlump the rocking horse when a unicorn grants his wish to explore the outside world in this magical adventure story. When Sugarlump the rocking horse longs to see the world, a magical unicorn with a silver horn and sparkling blue eyes grants his wish and turns him into a real horse. But after trotting around the farm, galloping around a racetrack and even dancing at the circus, Sugarlump learns to be careful what he wishes for. Luckily the unicorn has one more wish to grant.