Horns & Wrinkles, by Joseph Helgerson, 2006

Claire's troubles begin when her nasty, pillowy cousin Duke drops her off a wagonwheel bridge over the Mississippi River. She floats down on a puff of fairy dust. Things go rougher for Duke-- he sprouts a rhino horn for a nose, and his parents (and dog Duff) get turned to stone. So begins a fantastically inventive and irreverent farce involving river trolls, rock trolls, shooting stars, riddles, bullies, catfish, long-lost uncles and brothers, muskrats, and a leech or two. As twisty and "rivery" as the Mississippi herself, well worth the journey. Recommended.