I can't find that nymph serendipity. Some users speak of a sign in fron…

To the left of Vershema there is a woods. take the dirt path and at the fork go north and take it as far as you can at the end you will find the trolls surrounding the fairy.

After you have killed the trolls she says to meet her in Stardale Glen. Where is that?????

If you sail to the top of the island you will see a place were there is an entrance to a forest. Go throught there and you will find Stardale Glen. Just follow the path to the top and you will find Serendipity.