I am a woodsman, so I have the farming craft, and I did the quest/tutorial one and sold the onion for 5 copper coins or something. And none of the things we grow give us anything more? So someone told me the point of farming is so we can sell the crops to cooks. I stink at selling things though, and I don't have a kin yet but I'm sure whatever kin i get to be a part of will have plenty higher farming levels giving away the crops. Plus I sort of found farming annoying, because i mean a workbench is easy to get to and we can use any one anywhere but not farming land. I was excited at first to get farming until I saw it has no benefits but taking up invent space right?
As a Woodsman, if you don't enjoy farming you can completely ignore it. Your vocation is focused on the Woodworking craft, and you'll use Forester to gather the wood for that.
Farming is a Gathering profession, just like Forester and Prospecter, but instead of finding nodes to gather you sow and harvest your own fields. Just like Foresters don't really make anything with the wood they gather (they just treat it for others crafts to use), Farmers only make and process things for other crafts (mostly Cooks) to use.
My first toon was a woodsman, my second a tinker, so I primarily farm for my own cook.
however, while still on my first toon, I noticed that some produce sells better than others. It wasn't until I had a cook and learned the recipes to realize which ones were more important.
Also, just as drops aren't worth much at lower levels but vendor trash makes you more money at higher levels, mats are the same way. Farming takes far too much time (especially after Turbine's latest changes) but it's also very easy. It's only at the higher levels, when people get into big group skirmishes and begin raiding that a lot of folks who previously farmed stop doing it due to time constraints.
The craft will never make you much money except for crit items, but at the higher level, the key grains and produce will keep a nice, steady trickle of money coming in if you want. Me, I found that money rolls in enough that I only ever ah from farming if I make too much for my cook. I check my kin, to see if folks want overflow, then ah the extra.
It'll never make you the money your selling hide and wood will make you, so don't worry too much.