Hmm, because you seeking for herb mobs, I think you have no buffer or ch buffs. That means that you have adventurer buffs only.
Ok, lets look what we have:
1. ev - drops herbs, some x3 mobs, but max lvl 53 I think.
2. fields of masacre - drops herbs, mobs vary from 53 to 58. But usually occupied by bots. Also you can go a little to North or east of devasted castle to hunt on undeads.
3. Lair of antharas entrance - really great exp from 58lvl snakes (Cave keepers), but no herb pots.
4. Giants cave - hmm, not so good exp, some xN mobs, but I didn't suggest to go there without proper buffs in yours lvl. No herbs, some stuns and group mobs.
5. If you are pro, you can try to hunt on group mobs east of Oren. They drop herbs I think, but also bites painfull.