What is the function of the mice in chapter one?

Mice are important in the novel, and they are even a part of the title. Mice are something that Lennie remembers about Aunt Clara. In fact, her reaction to mice is the only thing he remembers about her. In the first chapter, Lennie is introduced with a dead mouse that he's keeping in his pocket. The mouse gives him comfort; he likes to pet it because it's soft..... and it's his. He know the mouse is dead, but that isn't an issue for him. From this, we can see that he really doesn't understand life and death per se....... he only understands the comfort he gets from petting its softness.

The function in the chapter is to allow the reader to understand Lennie. He's just a big kid, he doesn't understand maliciousness or the intent to hurt...... the mouse's death foreshadows future events.