Bounty Barn, Nomad Highlands, east of Umber Hollow. Here, saved you all a click.

Thanks for this. I got out of the habit of closely inspecting the crops of places I was going past, since they all had the same selection of crops, read the crops that grew wild in the area. I only would have bothered closer inspection if there had been a quest or lore chain directing me there, which there isn't.
In short, this is a lifesaver. The fact that they only seem to grow here is intensely irritating. I'd only found three pieces of straw as random loot.
Thanks again.