Originally posted by GunsForBucks:

The little saplings in the meadows will often drop resin.

In my experience they drop quite a bit of resin. Harvesting the saplings can usually be done in just one or two strikes with an axe, so you can mow down a lot of them quickly. It also has the benefit of clearing the forests around your base making it easier to move, see enemies, and fight. And you also get a lot of wood.