Why are you keeping things? If it's just for you, like a scrapbook, then keep anything you want as a momento. If you are keeping it because of college, then consider how it will be used. A college *may* ask for a graded English paper, or a math test, or a history paper. They won't ask for ALL of it, just a sample. Your binder is a collection of samples, so that you can hand one to a college if they ask for it. Now, an artist may be asked for their portfolio. My kids aren't artists at all, so I had very little to show for it when we did the notebooks!
If you want to eventually make course descriptions using your records, then it can help to make a copy of the front cover and table of contents from the textbooks you use. If you are making course descriptions, that information will come in handy while you are writing things up.
Learn much more about how to keep high school records in my “Preparing to Homeschool High School” DVD set.