Small pill bottle in an obvious location.
Anyone who was around when 1999 turned to 2000 remembers the argument about when the millennium ends. Chronologists the world over had their moment in the sun explaining that numbering the years started at 1 A.D. therefore the first millennium did not end until the year 1000. Even Seinfeld helped to explain this when Jerry tweaks Newman about the date of his Newmanium party:
Jerry deflates the Newmanium balloon
Same rule goes for centuries and decades. This cache was published on December 31, 2019 which is a full year before the end of the current decade.
A crisp dollar bill and FTF goes to Fur007!