Considering that Edible berries in the game as they are now are a pain in the ass to harvest, what with each successful gathering lowering the quality of the soil for all subsequent harvests, a thought occurred to me as to why berries aren't able to be picked from Mulberry trees? I have fond memories growing up of picking those tart things (that stained your fingers and clothes horribly) and enjoying them when ever they were in bloom.
Granted I understand that there needed to be a way for Silk to be introduced into the game, but trees already have multiple 'choices' for harvesting sprouts, bark and branches. Why couldn't Mulberry trees have the same for Farming? Being able to gather between 5-10 berries per tree I feel would suffice.