Fancy Herringbone -  great pattern for anything that needs to be very flat - it doesn't curl at all

Knitted in a multiple of 3 sts, + 1 and 2-row repeat.
Row 1 (Right Side): Knit 1, * yarn over, slip 1, knit 2, pass the slipped stitch over 2sts; repeat from * to end.
Row 2: Purl 1, * yarn over, slip 1, purl 2, pass the slipped stitch over 2sts; repeat from * to end.