If you tour the Bureau of Printing and Engraving in D.C., you can buy uncut sheets of current banknotes. You can also order them on the web site at:

http://www.moneyfactory.gov/store/section.cfm/69

It's possible that if your sheets are very old, they may have added collector value.

Note that star single star notes have been sold direct to collectors for some time. I don't recall seeing uncut sheets of star notes, though.