It is Pretty City Day in the Big City. George is a member of Steve's pod, a group of people that will help clean up the city, and his group has been assigned to clean up George's street! The winner gets their face on a poster. George begins his work cleaning the city but a lot of the things he sees being thrown out are amazing, too amazing to put in the trash. When he decides to bring those things home, he winds up with more keepsakes than trash! That's when The Man With the Yellow Hat explains that a collection is made up of things that are related or the same, like his collection of pig sculptures. Now George has to decide what to keep and what kinds of the same things to keep.