Fake grafting, or mock grafting was one of the first ways I learned to join knit fabrics together. It's not as "seamless" as a traditional graft of live stitches, but it often works well enough.

Fake grafting can be used anytime you are joining the cast on and/or bound off edges of your knitting together. It works well for shoulder seams, infinity scarves or bag straps that are worked in stockinette stitch.