Along with the candy and other goodies I hand out to Trick or Treaters, I always add a gift tag with my name so parents will know where my treats came from. To make the gift tags "green" I use printable bookmarks with Halloween designs.
You can find a sheet of free printable Halloween bookmarks on my web site - use them as Halloween party favors or gift tags, your choice. These make nice classroom party hand outs, too - no worries about sugar or food allergies.
Need printable bookmarks for other occasions - visit Bookmarks and Bookplates for a huge selection.