You can, it's called Appliquilt. If you want raw edge applique you can just use your straight stitch as close to the edge of the appliquéd piece. I prefer doing it with the buttonhole stitch, but it doesn't look quite as nice from the back.
Couldn't see anything on a quick search other than McKenna Ryan's, have a look & maybe it might help.
http://pineneedles.com/Company/help.asp