Teachers always hand out supply lists on the first day. These state what your son should bring to school. Education.com also has general lists on the "Back to School" page, link below.
I would recommend a backpack at the least because he will be bringing home papers from class. Once he has a backpack, you should add at least a few items from the first/second-grade list, then get the specific items on the teacher's list after the first day.