Ok, this doesn't work for everyone, but the Gol Bolar Quarry, down below Iron Forge is a goldmine for copper outcroppings and the herb earthroot.
Be prepared, there are tons of mobs there, they can aggro, but most are not excessively tough and I did fine with my lev 10 mage. Also, they don't like to chase you and if you run up the hill, there are a group of guards that will kill any that come to far.
So, back inside the quarry, copper veins and earthroot keep reappearing all over the place all the time. Plus, the mobs drop a lot of linen and occasionally nicer items. Keep an eye on the entrance area for the quarry as well, there are a few recurring earthroot spots up there as well. I've gotten 40 earthroot in an hour there multiple times.