You are looking for something small that is well guarded, BYOP in case the one provided is gone.
This cache is placed in the Willow Park Ecology Centre.
In order to sign in you will need to get past the Troll that is guarding the cache. Hopefully he only scares off the muggles and you can over come your fears and take the log book away from the Troll. His name is Brent, and if you call him by name and say please he may give you access to the prize. You're in luck for the time being the troll has taken a little vacation, but he could be back anytime!