Pins on their jackets or other items are not for trade. Any guest can trade one pin for one pin with a cast member as long as both pins have the copyright Disney logo somewhere on them. There are only a few exceptions to this rule. There are active pin trading locations inside Disneyland and one at the hotel. However, Pin trading can take place anywhere you see someone wearing a lanyard, vest, hat, or other article of clothing with pins on it.
Some people even carry around large folders of pins, but they tend to hang around the pin carts.
The pin carts have a wide selection of character and other pins and are always staffed by a cast member with a pin trading lanyard. Pin carts are where you'll find the largest collection of fellow pin traders like yourself. Pin traders walk by all day long. So if you wait at a cart for a few minutes, you're sure to meet a guest who has pins of their own to trade. There are three other locations where you might find pins to buy or trade.