For the first round, skip the 2 chains closest to the hook and insert 12 double crochets into the first chain you made - the one closest to the tail.
Join the round with a slip stitch into the top of the first double crochet you made. Pull the tail to tighten the circle - this will be the center of the coaster.
You've completed the first round, and should have a circle with 12 double crochets (as well as the chain 2 from the beginning of the round).
Round 2:
To start round 2, chain 2.
Insert 2 double crochets into the first stitch.
Continue adding 2 double crochets into each stitch all the way around. Now slip stitch into the first stitch you made.You should now have a circle with 24 double crochets (and the chain 2 from the beginning of the round).
Round 3:
Chain 2 and insert 1 double crochet into the first stitch. Then insert 2 double crochets into the next stitch.
Continue this pattern for the whole round, alternating 1 double crochet and 2 double crochets.Slip stitch into the first double crochet that you made in this round.You should now have a circle with 36 double crochets (plus the chain 2 from the beginning).
Round 4:
To start round 4, chain 1 and insert 1 single crochet into the first stitch.
Now skip the next stitch (leave it completely empty).
Insert 5 double crochets into the stitch after the skipped stitch.
Skip another stitch after the 5 double crochets (leave it empty) and insert a single crochet into the next stitch. This has made the first petal, or scalloped edge, for the coaster.
Repeat this pattern all the way around: single crochet, skip stitch, 5 double crochets, skip stitch, etc.Once the round is finished, make a slip stitch into the bottom of the first single crochet you made.
Finish off the coaster:
Cut the yarn off from the ball, a couple of inches away from the coaster.
Fasten off the yarn.To do this, wrap the loose yarn around your hook and pull it back through the loop left on your hook. Pull the loose yarn tight, to stop the coaster from unravelling.
Use a yarn needle to sew in the ends several times. You'll need to do this for the last piece that was just fastened off, and for the beginning tail (at the center of the coaster).
Cut off any excess yarn, close to the coaster.
Optional: Use the rest of the yarn ball to make 5 more coasters!Your crochet coaster is complete!