These are Disney pins that are usually Disney characters of some sort - we have a ton of Tinkerbell pins (some are of the castles, etc).
You can trade with resort and park guests but the most exciting trades are with disney cast members. the CM with the yellow lanyards (the things that go around the neck) can trade with adults and children. the CMs with the green lanyards can only trade with children and they usually have pretty good/rare pins in the morning. I have not been in a year so I cannot tell you what is "hot" now but we were collecting a Tink series last December and got four out of four pins.
Beware of trading with resorts guests. someone conned my daughter into a trade when I was chasing down a 4 year old and when i got back to her, they would not give her rare Tink pin back. I should have gotten CM, management, or security involved but the family took off. I spoke with a manager level cast member and explained the situation and he found the pin and shipped it to my daughter. I told her Tink sent it because she was such a good girl and those people had been deceitful. Now, we keep the "good" pins tucked away.
trading is fun though. you can get the lanyard with some pins I think for about $25 and they also sell cards of pins. I think that is four pins for about $16.00. it can get expensive so if you see any of the cards/pins at a disney outlet you may want to snatch them up.