The first one is probably circumstantial. Mushrooms are generated randomly at all times (in fact, that's frequently how I keep my tribe from starving when I'm testing population limits). You should look for mushrooms in VV3 during and right after rain. That's a period of time when there are ONLY mushrooms.

The second is a frequent misunderstanding about how fruit works in VV3. The amount of fruit is added the second the fruit is picked up (or picked from the tree), not when it is added to the food bin. That's different from all other forms of harvesting.