'A Seed That Grew' is a children's storybook about a girl who plants a seed that grows into something extraordinary when she nurtures it with passion, love, and dedication. The synopsis of the book emphasizes that small ideas, nurtured diligently, can create something surprising and ultimately fill the world. Through this story, children are encouraged to not hesitate to cultivate their own dreams and understand that with the right care, big things can start from something small.