hi Anne, yes you can use them, in several ways. Look into liberally covering iron-on interfacing with threads, wools, fine strips or diced fabric - [we here call this confetti ] ribbons, laces etc. Also some use them on solvy or other water soluble, place another sheet on top, and stitch well over the lot free-hand with pretty machine embroidery threads. After that, wash out the solvy, and you will end up with something like a scarf, or if you do enough and thick enough, you can make your own fabric. If you check out machine embroidery stores, you should find the wash-away 'fabrics' and threads. They should be able to help you out with advice as well.
But be careful, or like me, you could end up with a shed full of bags and boxes of odds and ends that hardly ever get used. lol
Cheers