Each mushroom in a patch starts of as a tiny baby mushroom. They can grow over time, getting bigger and gaining more weight. Soon I will add logic where bigger mushrooms may also have more effect when consumed as opposed to small ones.
Besides growing, mushrooms can also be collected by selecting a mushroom patch and then right clicking on it. This will call a minion to the patch for collection. Since mushrooms are rare and grow slowly, minions will be careful when collecting and leave some mushrooms behind to keep the patch growing (unless there is only one left - if you command a minion to harvest a patch containing only one mushroom, the patch is removed completely). This allows you to keep mushrooms growing if you want to keep a steady harvest.
The growing algorithm is a bit shaky so I'll revisit it if there aren't any errors with this new version sometime in the coming days.