|I think a bigger problem is that you actually own a mortar and pestle.|
But this does bring up the question--How many mortar and pestles does a person really need?
My answer is Four.
One for herbs that you can eat--basil, thyme, sage, etc. Basically, this mortar and pestle can do double duty both in your circle and your kitchen, If it is safe to eat, you grind it in your "food safe" mortar and pestle.
The second one is for plants that you should not be eating--nightshade, wormwood, belladonna, etc. Basically, you want to keep your poisons away from anything that you might be ingesting.
The third mortar and pestle is for resins--frankincense, myrhh, etc. I prefer this one to be smooth bottomed because resins tend to get into the grooves and never come out.
And for those who are doing alchemy (other than the plant variety--which a lot of people insist is "not really alchemy"), you need a fourth mortar and pestle for metals and other stuff. This mortar and pestle often needs to be made of stone or metal (depending upon the school of alchemy you are working in).
So there you have it, you need four mortar and pestles.
(If you really need a mortar and pestle for the first two types and live in the United States, consider buying one from my wife--Celtic Soul Jewelry and Pottery.)