This was a pain! I did finally find one though!

respwan time around 3-3.5h

just found an everlasting herb not sure if i gathered it from an everlasting herb or a wild herb though

the location i gathered it from is not listed here but it is only listed as gatherable from everlasting herb gatherables

Gather wild herbs at the se of florin. worked for me after 20 gathers

Annoying to find, but they have small plants that you can easily miss.
Here's where i found one and what it looks like:
https://i.imgur.com/CrCmyWs.png

this will help you much better Everlasting Herb

Florin, take the path right to Valentin and walk up the hill. You will find a lost kite on the floor, a little further to its right there is a birch with a tiny pink flower ( = everlasting herb) next to it (have a close look, its quite hard to see!)

got it from random drop while in duch island