I'll relay some personal experience with the Grass Knot; When I started finding uses for flat woven nylon and flattened tubular nylon strapping (tie downs on motorcyeles and lashing to the car top of soft painted canoes) I went to ABOK and found this knot. Seemed like a good idea at the time. Then re-read ABOK and see that all the material mentiond is expendable and not to be reused. This seems to either slip and then jam or just jam from the beginning. I have nothing to recommend it in material you intend to reuse or to secure anything of value. I have used it to fine effect for making cane bottom canoe seats and other such.
Just to not leave a loose end on this thread. I recommend the use of a cinch knot, ABOK # 234, on a ring. Then the flat material is wonderful for not chewing up the paint on the canoe and good for the bundles on the motorcycle so all is not lost.
I use all sorts of rings (recycled or purchased new) and haven't lost my stuff or had to cut the knot (not the experience when using the grass knot).
You will also find the climbers use some tape knots as shown in Phillpott and others... plenty of web sites I supose.. I am using some of the ones from Lindsey P's books to good effect.
One thing I would recommend to anyone starting out; Buy some inexpensive cord and ruin it. Get some hands on experience finding out about a jammed knot. The web sites, the books and the collective information is 1000% better than 50 year ago, but plenty of missinformation too. That said there is nothing like holding a knot that you can't undo (not with your hands, not with your teeth, not with your spike or a brickbat) and wondering why you did not learn a better knot before this happened.
Thank you for opening a good thread and giving us an oportunity to cast our ideas. I hope to see you on Forum as you work your knots. We have a great show coming up for the Equinox Weekend, wish you could join us. Going to be a lot of fun!