It seems like a good way of implementing this would be to have the more desirable jams made from fruits that are found like chantrelles or rustroot. This would create a more concrete reward for exploration and gathering, as right now the only thing valuable in the forest is killing bears. (and finding mines if you're looking for that)
Apple preserves: no fep's but can be eaten plain
Mulberry jam: no feps but can be eaten in parts to provide "condensed food" (ie you could fit 10 berries worth of food into a jar or something)
Salmonberry jam: salmonberry bushes are about as hard to see as chantrelles.
Blueberry preserves: as hard to find as rustroot
Boisonberry jam: Hard to spot, but provides reasonable psyche or dex fep's (or something else to make it valuable.
I guess sugar ccane would fit well with implementing jams, but I'm not sure how we would grow it. Greenhouses maybe?

I once dreamt of crafting beautiful thane's rings... then I discovered Big Bear Bangers. Now I smash beautiful things.