Over this side of the pond bag is when you place backing right side down with batting on top, then place right side below backing with the right sides touching. Sew all around except for a small section through which to pull the material to the right side. Stitch up space.
Before doing all above ie bay out or bagging place in pen holder etc.
Thanks. I do that all the time and guess I don't really have a term for it, outside of sewing right sides together and then turning right sides out.