Tolkien’s dragon sickness comes from the whole Nibelungen cycle, in which the dwarf Fafnir turns himself into a dragon to keep the gold hoard. Depending on the version, the gold is created by a ring that Odin and Loki tried to claim but its owner cursed it because fuck those thieving gods. Several of the Germanic variations of the cycle put a lot of focus on greed for that hoard leading to the destruction of the Burgundian kingdom, including Atli (Attila the Hun) trying to get a piece of it, until the gold is tossed into the Rhine so that no one can have it.

Large parts of the same Germanic tales are heavily inspired by the feud between two Frankish queens, Brunhilda and Fredegund, the murder of Brunhilda’s husband Siegbert, and the migrations of the Burgundian tribes that ended in the modern French region of the same name. They (or rather their predecessors) were all involved in the defeat of Attila at the battle of the Catalaunian Plains. There’s no particular record of gold greed being involved in any of it, but it’s curious how that’s what the Germans remembered of it.