Central Park has been home to mysterious troll's for thousands of years. Once they found the bridges to live under, they began collecting treasures to keep in caches near their home. They don't mind people walking about, so long as they don't disturb their home. If you trade a treasure from the Cache the Troll will surely be happy.
Gur Gebyy znl yvir haqre gur oevqtr, ohg ybirf gb graq uvf tneqra obk arneol