In There's a Rock in My Pocket, young Timmy discovers a smooth, shiny rock in his pocket and sets off on an adventure to learn more about it. With the help of his friend Mia and Mr. Green, the friendly park ranger, Timmy learns that his rock is a river stone, shaped by the flow of water over many years. Along the way, Mr. Green teaches the children about other types of rocks they can find while exploring, such as quartz, granite, and sandstone. The kids learn how to identify these rocks by their unique characteristics, turning a simple walk in the park into an exciting geology lesson. By the end of the story, Timmy realizes that every rock has its own special story, making each one a tiny piece of history. The book encourages young readers to explore the natural world around them and teaches them how to identify different types of rocks.