This article is from the Final-Fantasy and other Square Soft Games FAQ, by firstname.lastname@example.org (Nick Zitzmann) with numerous contributions by others.
Confused to the purpose of those junk items? They seem to do nothing but
take up space in your inventory, but Wayne can put them to good use.
Take your junk to Wayne. After collecting 300 pieces of junk, Wayne can
make you one of the game's most powerful weapons.
Be careful, though. If you let Wayne decide on something, you usually
get an inferior item. Although there is a chance you can get the mighty
AK-47 assault rifle this way, you might just end up with a completely
worthless "Super Junk" item.