In the online help section, under products it tells you what building you need to make each product. That was very helpful once I found that part of the help section out. I think it would be even more helpful if you labeled the building size you need as well, small (s), medium (m) or large (L). For example Turnips, my personal favorite, and bane for my first 20 days of playing, can be only built in a (L) farm.
