This political button is from Richard M. Daley's 1989 Chicago mayoral run.
The green shamrock represents Daley's Irish heritage.
During the 1989 Chicago mayoral campaign, Democratic candidate Richard M. Daley used political buttons adorned with Irish shamrocks to appeal to city's large population of Irish-American voters. Daley won the election and served as mayor until 2011. His father, Richard J. Daley, served as Chicago's mayor from 1955-1976.