You can create a seamless circle by changing the beginning chain into a different stitch with the yarn tail.
The basic structure of Double Crochet Stitch ( 0: 25 )
Double Crochet ( 0:52 )
Treble Crochet ( 6:53 )
Single Crochet ( 9:30 )
Half Double Crochet ( 10:34 )
Supplement
If you decrease at the beginning of the row, make a stitch without a head by reducing the beginning chain stitch by one.
dc3tog
sc2tog
