I unlocked this in around 10 minutes, I did this in the blackwater area but i recommend going to the side of rivers and streams and activate your Eagle Eye by pressing
and
i have a video provided to show what you're looking for. when you activate the eagle eye the scent of the herbs will come off the plant and will attract your attention. stay away from towns and stay in the areas with no much activity and stay by streams!
for visual learners there’s a video attached.
happy huntin