There are plants in Felwood that may be saved from corruption when Cenarion plant salve is applied to them.  I know how to make the salve from several different kinds of items; based on your skill set, you may find that you have multiple options to assist me.$B$BYou will also need a Cenarion beacon for your work here; it is a device that allows you to see the taint and corruption of nature that the naked eye will miss.