The Diamond Factory — Julie Harris

Gray's a country kid who finds Boo, a magical critter that came out of the farm's bore. He's cute, he talks, he's great company, but the best thing about Boo is his poo. Boo is a little diamond factory, and he's been on the surface too long and needs to go home to his family. But home is deep underground. Can Gray help Boo find his way home?