The most commonly seen pins are those 3 1/2" ones from around 78-80. I believe you could originally get them at stadiums and through mail order. If you have any old baseball digest issues from that time, you can find all kinds of great ads for stuff like that (plaques, patches, buttons, posters, etc). I would assume Winfield is in this set.
Then they issued some pins in the late 80s. You can find those in around the 1" and 3 1/2" sizes. They can be tougher to find for some reason. Winfield is probably in that set.
Finally in the early 90s, there were some baseball buttons found in packs. Yellow and red borders. Those are cataloged in guides, but I don't know if Winfield is in the set. Likely though.
Of course, there are the Topps buttons from 84 as well. He is in that set.