How about picking up a couple of daily use type pocket knives from Walmart or the local gun shop and add them to the mix.
For stuff to cut, (other than bread
) try picking up some of the different geo textile materials used in road and pipe construction, heavy plastic and rubber, plastic banding material, various light and heavy foam and plastic wraps, etc. Then soak anything porous in a slurry to paste of mixed mud, sand and fine stone. Fabric packed in dried mud and dirt is also something to try.