You have to craft Honey Butter Beer for a chance to get this Sweet Honey Butter Beer. Ingredients can be found at Eiza in Rothun.
Sweet Honey Butter Beer opens hidden locations for Mokoko Seeds
Lake Shiverwave - https://imgur.com/c111pjf
Breezesome Brae - https://imgur.com/pGDJ06c

(I will update when I find more)

Buff holds 10 Min.
Another Spot:
Queen's Garden

I have a sneaking suspicion that you should use it in the vicinity of the drunkards you sometimes find in the oddest locations across Rohendel that mention that all you need is a good drink to have a good adventure. They may be pointing out where the hidden seeds are.