Three years ago I had my first and only kidney stone attack. I was told I had four stones in one kidney, one of substantial size. Although I occasionally get weird twinges, I have never had another "attack". Do they go away on their own, or do they just lay dormant?

If they were very small, chances are you have passed them already. If it was position all the way up, sometimes it stays there until it is big enough to dislodge itself.
If you are prone to kidney stone, you will find yourself having another attack in the future. You probably want to see your doctor to order a ctscan of the kidneys making sure they are not enlarged. Just drink lots of water. Fresh coconut juice is very alkaline, it aids kidney functions and dissolves kidney stones.