This cache was originally part of a series which included all of the horcruxes from the Harry Potter series. The aim was to collect all the horcruxes before taking on the final cache; Voldemort. Unfortunately I've had to archive some of them and the puzzle aspect but I've left a few popular ones out there. Hopefully I'll re-do it one day! Sorry to those who didn't get to complete the series.
Tom Riddle's diary:
The diary is secretly given to Ginny Weasley by Lucius Malfoy, without her knowledge. After realising the the book is starting to control her, Ginny disposes of it. It is then Found by Harry, who later destroys it using a Basilisk fang.
You are looking for a small clip lock pot. Please replace carefully as found, and be aware of muggles!