I recently played in an adventure with a new group, and after killing a dragon, the rest of the group started talking about butchering the dragon, harvesting its scales, blood, eyes, fangs, etc., specifically so we could sell them for money. I was shocked that we were talking about breaking down a sentient creature for parts, but both other players and the DM seemed to feel like this was a normal thing to do. In further research, every group of D&D players I've asked has told me this is something they've seen in their games, or heard about as a normal thing to happen. Somehow, in 20 years of playing D&D, this idea has entirely missed me.
I've checked through a few questions here (including a 5e one here) that ask about the mechanics for harvesting dragon parts, and generally what I've seen is that in 5e and 4e, there were no mechanics for this, and in 3.5 the only source about this was the Draconomicon. The one exception being the rules in 3.0/3.5 about how to harvest dragon hide, specifically, for Dragonhide Armor.
It's strange to me that something with no apparent rules justification is treated as such a normal thing, so I'm trying to figure out where this idea comes from. Specifically, I'm looking for the first time in D&D that there were rules that specifically showed what dragon parts were harvestable, how much they could be sold for, or any other indication that harvesting dragons parts for money was a thing supported by the rules. Magic item creation rules that gave benefits for using dragon parts other than hide would also work. If there are no such rules in any D&D edition, then showing a non-rules source supporting dragon harvesting in D&D (maybe dialog in an adventure or something? flavor text somewhere?) would likewise answer my question.
Where exactly did the idea that you could sell dragon parts come from?
Best Answer
Way, way back.
As to where it first appeared in the rules, the first edition to include rules for selling dragons was... the original game! "Subduing Dragons" was a special rules section in the Monsters And Treasues supplement was the first stun damage rule in any RPG, and selling the dragon for lots of GP was the explicit reward for doing so. Later supplements expanded on this. The 2e Draconomicon added a description of the butchering process (dragon's blood could be reliably sold at 200gp/pint, as long as you could bottle it before it putrefied and combusted). The 3e Draconomicon presented 'Dragoncraft Items'. This was greatly expanded on in June 2005's Dragon Magazine, with the subtle cover title "101 Uses for a Dead Dragon".
As to where chopping up a dragon comes into play in the source materials...
Gary Gygax spoke German as a child, and later studied Germanic legend. This is relevant because Germanic and Nordic mythology is rife with the use of dragon blood or other parts:
But of course, these tropes are older than the German middle ages; parts of dragons were valued medicinally, particularly in the classical period.
Finally, I leave you with the song Every Little Piece from the Disney movie Pete's Dragon, which came out in 1977, the same year that the Holmes D&D Basic Set came out.
Even if players weren't German history buffs, the idea of carving up dragons for big rewards was definitely in pop culture at the time.