One of the first things that most people learn how to crochet is granny squares: they're easy, quick, and use up little bits of wool rather than needing to buy big quantities. You can then put the squares together to make things like blankets and cushions (and more, if you're creative). Here's my first go at a cushion cover, not yet attached to a cushion:
When you attach the squares together you can do it with crochet, rather than having to sew them. Gives a nice neat edge. Some people actually crochet the lot together as they're going, building one on what's already there, but I made little ones and attached them in rows.