My daughter's 2nd grade class spent the year studying the Charles River in MA so for their end of year cake I made them a River Cake. Rocks were made by mixing graham cracker or oreo crumbs with frosting and letting harden. Dirt was crushed oreo or graham crackers (depending on if it was dirt or sand). River was made with blue gel over white frosting. Signs were copied from the town signs here in Massachusetts and were made with paper and toothpicks. Thanks for looking.