My wife rolled her eyes when I told her about this one. Yet, it does solve an annoying problem. When I sit at a table which does not sit flat on the floor, it can be rather annoying. Maybe there is something that can be stuffed under the shortest leg but not every time.
Step 1: Make a Filler Strip
My solution is to cut a strip of thin cardboard about 1" wide and the length of a dollar bill. Store this strip in with your money. When you get one of these rocking tables, pull out the strip and double it over enough times to fill the gap. No loss if you leave it there for the next person to enjoy.