Research papers by their very definition involve research. But when the subject is English then that immediately narrows the focus of what you're looking for. You will begin your research by calling on two main resources -- your local school or college library and the Internet. Both have their uses and specific benefits.
Obviously the Internet is far reaching and access to it is simple. However because the resources are so vast you need to be precise in what you're looking for. You could spend a lot of time and waste that time by not focusing specifically on your target. Your college library has the benefit that the librarians are trained and know where material is and can point you in the right direction provided you can explain exactly what you're looking for.
Brainstorming always works better when you have at least two people involved in the activity. Too many and it gets a bit messy but certainly two or three people are good because they can bounce off one another. But you need to be specific.
You're looking for English topics for a research paper. So what aspect of the study of English really appeals to you? Is it a particular author or a genre or a time or period? The point is what is important to you and use that as the starting point for your brainstorming. Make sure you have a good scribe, somebody who can take down the ideas as they are called out. And don't be afraid to bounce off one another -- that's the whole purpose of brainstorming.
And just to get you off on the right foot here are some possible themes or ideas you could think about before you start your brainstorming.