Sophie's Souvenir Secret

Sophie is different, and she likes it that way. She wears overalls, eats black licorice, and likes to dig in her backyard. Most important of all, Sophie likes secrets --- any secret at all. When her neighbor, Dot, enlists her help to take care of a community garden, Sophie is surprised to discover an unusual secret: souvenirs are appearing there, and she doesn't know why. Who's leaving them? And why? All she knows is that she has to find out.