Harvestables

The plants, mushrooms, fruits and ores that spawn in the overworld can be harvested with a Harvesting Tool or by a pet with the Gatherer ability.

If a player has Overworld PvP enabled, more nodes of some resources are visible.

Plants and Mushrooms
These resources are used for potions. Most of these harvestables can also be acquired from Reward Caches, except for Roto Spores, Crown Foil, Sydazoran, Blue Moon Spores and Red Truffles.

With enabled Overworld PvP, more resource nodes are visible.

Ore
Ores are mostly used for artificing, and can't be harvested by pets.

Enabling Overworld PvP does not increase the amount of ore resource nodes visible.