Beautiful hand carved walnut skull.
In the American Hoodoo tradition, walnut leaves and nuts are used to put jinxes on people. Walnuts are also used to “fall out of love”; Yronwode in her Hoodoo Herb and Root Magic describes a ritual where you make a tea of nine black walnuts (husk and all) boiled in three quarts of water; boiling it till the water evaporates down to 1 quart. You bathe in this water, renouncing ties to the former love, and then throw the water out at a crossroads or against the tree. This kind of bath is not one for the bathtub, but usually done in a smaller tub. Again, we see this expelling or removing quality associated with the walnut present.
To make a wish/grow an intention, break open an English walnut and take out the meats and eat them. Write your intention as a positive statement “I am/have thingy” (versus I wish I had, or I will have, or I am not/don’t, etc.) on a very small piece of paper. Fold it and tuck it into your walnut shell, close the shell and use glue or wax to seal it. Bury it outside to “grow” your intention. Say it out loud as you plant it. (You can elaborate on this however you like, with suitable oils, incense, candles, chants, etc. suited to your intention.)
You can also use a walnut shell to create an abundance charm. Crack open the shell and remove the kernel as above. Add small items that correspond to abundance and anoint it with an abundance oil. In this case just stuff the skull with your ingredients. Seal with wax or glue and carry it with you or hang it in your home. You can elaborate this spell with any candles, incense, chants, etc. you feel are suitable.