I know that a few times I've been looking for a certain plant or mine to farm. Now this isn't really up to date but the site that I used so often and found really helpful was:

http://www.eyrdaian.com/?page_id=532

After a while you learn where they are and it's easier but til then that's the best. I figured that it's easier to put the link than link all the different maps that they have.