Kinoko Machi: Kinoko Chinchin Kokufuku Shuukan

Once upon a time a great famine struck this land, but suddenly appeared mushrooms became salvation for population.
Nowadays people continue to live in coexistence with mushrooms. There is even a festival where millions of yen are given to a person who finds a talking mushroom. Main characters lives in a town where mushrooms are everywhere, so he hates them. He leads a happy student life and finds a girl he wants children from. But mushrooms never leave him at peace...

[From vndbreview]