Opposing Viewpoints is a database that has pro/con essays and other articles on controversial issues. You can find it on the ENG 1101-1201 guide. The "get started" page includes books and websites with more ideas for papers. You can also find a link to it on our A-Z list of databases under O.
Here are other databases that are most used for the ENG 1101 and ENG 1201 persuasive/argumentative papers.