Print out rosters for all of your classes. Use a three-hole puncher to prepare these rosters for placement in a binder.
Write the name of the item you are sending home at the top of the printouts. This could be "Zoo Field Trip Permission Slip" or "Classroom Contract 2011" or something similar.
Have a stack of these items ready near the front of your classroom. At the beginning of each period, have students file in. Each student should pick up an item and initial his name to show that he received it. Monitor this process to ensure that everyone who receives an item, initials for it.
Place the rosters in your binder. Keep this binder in a handy place, so that if a parent later says he did not receive the item, you will have a record that you gave it to the student.