The spriggan cap is from Unhidden Leather Map - Which drops from Boarskin and Peiste Maps.
To do Maps you need to do a level 40 quest in Wineport, i dont recall its name.

I got mine as a christmas gift :P
On our server some mil gil on market board :/ as it is double luck to get it at all (first the unhidden map then the cap).

GL on gettin it