We've always been admirers of Heath Ceramics. The pieces are earthy and substantial, and have a nice feel in the hand. A friend just gave us the tip that a Kid's Set is now available from Heath Ceramics.
The set includes three pieces of tableware - a cup, bowl and plate - in primary colors. You also get flatware, designed by David Mellor, in the full set. Or you can purchase the tableware alone. If you're lucky enough to have Heath pieces in your home, this is a great way to add to your collection.