If you left a teleporter stone behind, you will find an ancient pyramid a bit north east of your starting location (which is where you would end up using the other ancient pyramid).
location of the Ancient Pyramids (71KB) - if you did not bring both teleporter stones with you to the wastelands
If you really need to get back to pick stuff up, etc. see below. However, your quest log gets cleared on entering the wastelands, so any unfinished quests may or may not be able to be completed.
Teleporting Anywhere, via hex editor
