I'm trying to use up odds and ends of baby yarn by making booties to donate. The pattern I'm using draws together the cast-on edge of garter stitching to form the bottom of the bootie. It's a cable cast-on. Can anyone advise the best method to use for the softest seam? I'm thinking mattress won't work in this particular case with the cast-on edge??? Back stitch? Whip stitch? Done right sides together? Thanks so much.
Here's the pattern: