I accidentally bought 100 yeast and i'm basically broke now because i can't sell it back. Please can you help
You should be able to sell back the yeast, but you can also just forage and collect some resources like wood from cutting trees and sell these resources to the Hawker. :)
I would sell back the yeast but it doesn't sell for anything
What quality does the yeast have and do you have any negative buffs which affect trading rates? Does other stuff like wood sell?
Brew beer with it and sell it either in your inn or to the hawker to try to use it.