Check your phone book for the local senior center and see if they'd like it. A lot of older people like to knit and crochet, but don't always have the money for yarn. In fact, right now would be a good time with the holidays coming!
If they don't, Craigslist, Freecycle, the local grocery store bulletin board or Ebay come to mind.
Och! it would do a seniors' home good to see a young good-looking chap like you at their door with yarn to spare. Cheer up the old folks, I say! (I have two parents living in such a home, and Dad still knits).
You could always mail it to ME!!!!!!! I teach a knitting class and we have been knitting shawls for residents at a local nursing home!! We can always use some new (to us) yarn, especially some that's machine washable/dryable!!!
Or if you'd rather look locally, check and see if your local library has a knitting or crocheting class. I'm sure they could use it.
Your local school....art teacher would probably be THRILLED.
I would...but I am the music teacher...but only because i would use it up myself! or teach the children.
I am confident you will find a useful cause.