The Smithsonian has Stubby (and his amazing vest) on display as part of The Price of Freedom exhibit. Make sure to click on "View this object in context" to get a better idea of the times Stubby lived in and the war he fought.
National Geographic Kids has a great overview of what World War I was like including details on what life was like in the trenches for the soldiers fighting as well as things kids did to help with the war effort.