If you're looking for silver nodes for jewelry crafting, they spawn anywhere a jewelry node can spawn in all the zones. If you aren't seeing much silver, it may have to do with your level, because the way the nodes work, you see about half that equate to your character level, and half that equate to your crafting level.
So if you're level 20, but your jewelry crafting is at silver level, a node would have about 50% chance to be pewter and 50% to be silver.
One other thing to be aware of is that jewelry nodes share the same locations as blacksmithing nodes, so if you aren't seeing many jewelry nodes then harvest any blacksmithing nodes you see and they'll have a chance to respawn as jewelry nodes.
Also, you can sometimes get a small amount of a jewelry material along with the usual blacksmithing materials when you harvest a blacksmithing node.