shred the junk mail and use it as mulch in the bed of the hedges or fill in low spots in the yard, once the grass gets cut (mulch-blade) over it, it disappears.
Personally, I keep waiting for someone to invent an automobile that runs on junk mail. Then we could look forward to getting the stuff! And instead of trying to get off mailing lists, we would all be trying to get on them. Win-win for us and the advertisers.