Simple Idea:
Each Herb that grows in the land also bears a seed.
Each seed can be planted anywhere, after a period of time a new herb grows where the seed was planted.
Depending on the type of land (forest, desert, water, mountain) it may or may not grow. Some seeds are corrupted, and won't grow no matter where they are planted.
Example:
A small red herb grows here.
A small red seed is on the ground.
Get herb
You get a small red herb!
Get seed
You get a small red seed!
travel
Plant red seed
You sow the red seeds into the fertile land with a wicked spade.
return later*
A small red herb grows here.
A small red seed is on the ground.
Another spin on this could be making farmer a perk at startup (much like heroism, addict, etc)
Druids and gnomes can farm automatically. Undeads and Demons cannot farm.
This would also create a "Seed economy" in the lands.
