Good afternoon, I am new here, and I will go introduce myself, but I have to ask this first!
I am a newbie knitter, less than 6 months. I make a lot of baby hats, and I loooove knitting, I recently came across a hat that I want to make very badly, but I can't figure out how the woman does it. It's basically a baby beanie, done all in stockinette stitch, but she doesn't edge it, and it doesn't curl! It looks like a long tail cast on.
It may be that the cast on edge is turned under to form a hem. You do it by casting on, knitting stockinette for 2-4” depending on how deep you want the hem, usually purling a row on the knit side for the turn and then continuing in stockinette. You can even catch the cast on sts after several inches so that you won’t have to sew a hem. Can you post a picture?
Large needles and yarn don't curl as much as using smaller needles and yarn, so that would help. The edges may have a crocheted edge around them, though the blue and green one looks like a cable cast on. Also, I've found that a lesser number of sts doesn't roll as much; I can do sleeves in stockinette and the wrists hardly curl at all, while the bottom edge of the sweater will roll up a couple inches.