Wikihow, a shared knowledge website, has a section on how to begin carving with a utility knife, they suggest using a soft maple as a beginner wood. Just make sure it is soft, carving the harder maple woods is NOT easy. Their tip is that if you can mark the wood with your fingernail, it's probably easy enough to carve.
This blog does not endorse carving wood or using a utility knife without proper knowledgeable supervision. Really! Don't chop your hand off because of us!