I’ve been working with bulky yarn that doesn’t “knot” well. Got me thinking of when my husband would go fishing and tie off monofilament line- which is very slippery.
So, I’ve been using the double fisherman’s knot and tucking that either under a stitch or running it through the stuffed toy leaving the knot inside the toy.
This won’t work for projects with small to tiny stitches as the knot can’t fit through the stitch hole.
Or you can do the Weaver’s Knot.