Chain 3.  Join into a ring with a slip stitch.

Round 1:  Chain 2.  Work 12 dc into center of ring, joining the last dc to the first chain with a sl st. 12 stitches.

Round 2: Chain 1.  Work 1 sc in first stitch, then work 2 sc in each stitch around, join round with a sl st in the first sc.  24 stitches.

Round 3: Chain 1.  Work 1 sc in each stitch around, join round with a sl st in the first sc.  

Round 4:  Chain 2.  Work 1 dc in each stitch around, join round with a sl st in the first dc.

Round 5:  Chain 2.  Work 1 dc in each stitch around, join round with a sl st in the first dc.

Cut the yarn, leaving a 6 inch long tail.  Draw it through the last stitch to fasten it off, then weave in the tail.

After you've made as many coaster tops as you want, block them lightly to flatten them.