There was a 4000lb Cookie found in Dresden lying in the mud of the Elbe during a period of unusually low (summer) water levels in recent years. Cookies are thin-cased blast weapons and are very unstable; they have been known to go off when jettisoned with an unarmed fuse. This one must have had a relatively soft landing in the mud and water of the river.

As ~Alan~ suggests; there must be lots in the Thames mud. One was found in a dock in Liverpool, when it was being emptied of silt.

Anon.