Überlingen is a town on the coast of lake Constance in southern Germany
Edeka neukauf at Lippertsreuter Straße 1 has an amazing dumpster - an entire row of small green bins that appropriately say "re-food". You should definitely go there well after the closing hour (closes at 21h, but go as early as 22h, preferably later), and do it at your own risk, since this nice food is behind a locked fence. It's to the left of the store, (no worries, it's not the compactor), but behind the gate with the wooden fence. For really short people it might be tricky (so bring a friend or a bicycle to climb over). Don't forget dumpster diving is illegal in Germany - be really quiet and keep it tidy. (Last checked: Oct 2014)
There is also a small Edeka in the center, again behind a fence (has some spikes but you could climb it on one side). It probably contains nice food, but if you decide to give it a try be stealthy since it's in such a busy location.
Completely accessible bins can be found behind Bio Fritz store at Hochbildstraße 1, at the far corner of the parking lot in a small walled area with no gates. It might be worth checking, though there doesn't seem to be much edible food. (Last checked: Oct 2014)