This is an easy pattern. Circles are easy to crochet in general in simple dc, sc, etc.: just keep increasing groupings one more stitch farther apart for each and every new row and the circle should lay flat even if you keep going like that for forever.
Ravelry: Van Ness Scarf pattern by Kathryn Nunes. For some reason the scarf I made didn't look quite as nice as the one in the pattern, it may be the type of yarn. I would recommend buying exactly what the pattern says