What are some things on the history of football that would be helpful to write a research paper?

There are actually quite a few different things you can write about for the history of football. You could start with the history of the game itself, and how was first played, or how it came into being. You could write about who the inventor was, where the first game was played, and how it became what it is today. 

You could also write about the history of the NFL. The NFL has actually been around longer than one might think, but it didn't start to become the most popular sport in the United States until about the 1960's. 

Or, you could write about the history of a specific team. College, professional, or otherwise. There is a lot of rich and interesting history and trivia behind every football team. 

Hope this helps!