Cubebox,
Usually, at every Olympics there's a lot of pins available at the Official Souvenir Store (hundreds of them)
Those are logo pins, mascot pins, venue pins, sport pins (for each sports), etc...
But those have no value for the real collector.
The real thing for them is the NOC pins, dated or not (NOC for National Olympic Commity). That's the pins given to the athletes for trade with others athletes. They are very hard to find. Dated means that the Rio 2016 Logo is add on the pin.
Some others collectors wants only Media pins, others Sponsor pins. Security pins, etc... Also very hard to find.