Cardboard buildings for school project? Please help!?

I have a school project where we have to create a town. My air-head partner just called me and asked if I can 'pick up some buildings', and I don't know what to do! I doubt they have them at an arts and crafts store like Micheal's or Joann's. Please help me:(! I don't have a lot of cardboard to use to 'build' them