First, buy some pillow forms. I got mine at IKEA for $3 each. These measurements are for a 20in.x20in. pillow.
Cut out a patterned fabric piece 18inches x 48inches.
Fold over the short ends about 1/2in. and iron down.
Fold over again the same amount and iron.
Sew down the folded edges.
Center your fabric right side up, and fold over each side toward the middle, overlapping until you have an 18in. x 18in. square. You want it to be 2 inches LESS than the measurement of your pillow, so the cover won't be baggy.
Pin the raw edges together.
Sew the two sides with a 1/4in. seam allowance.
Turn the fabric right side out.
Push corners out so they are nice and pointy.
Stuff the pillow form in, and you're finished!
Now for coordinating appliqued pillows...
Cut some solid material to 18in. x 48in.
Cut out a picture/design form your left over patterned material and a piece of heat-n-bond iron on adhesive and iron it on the back.
Cut closely around the shape.
Peel off the backing and iron onto your solid material, making sure it will end up where you want it once the pillow is sewn.
Add as many cut outs as you like, then sew around your design with a small zig-zag stitch.
Sew the pillow together just like the first one.
Now the couches aren't boring, and when the kids slime up the pillows, you can easily remove the covers and throw them in the wash!