No, there is no official lore
There is a simple mention of the oil of taggit in the 3.0 Dungeon Masters Guide, on page 80 as an ingested poison with a save DC of 15. (Note, the poisons entry is on an earlier page, this is the table listing various poisons). As near as I can tell this is the first official mention of taggit as a poison, and there is no origin for it listed, nor can I find any other official source that lists an origin.
Official mentions in various editions with no source (That I have found):
- Powers of Faerun
- Complete Adventurer
- Book of Exalted Deeds
- Dungeon Masters Guide
- Dragon Magazine #349
- Song and Silence
- Lords of Madness
- Enemies and Allies
- Dragon Magazine #131 (Beasts of Aulbesmil)
There is a 3rd party publication by the company "Blue Devil Games", and taggit is listed in their sourcebook on poisons Poisoncraft: The Dark Art, on page 87 with taggit root as the source:
OIL OF TAGGIT*
Steeped taggit root; gray, odorless oil; hedge root family; ingestion DC 15; none / unconsciousness 1d3 hrs; Craft DC 20; Price 300 gp; Exposure DC 4.
The * next to the name indicates:
Additionally, all of the poisons from the DMG appear here, recast using the new rules and fleshed out with greater detail. These entries appear with a * following the name.