You could carry an amethyst crystal around with you. It is a calming and relaxing stone. If you carry clear quartz with it the amethyst's power will be amplified, thats because what quartz does is amplify energy.
There may be a local store you can buy these from, if you don't have one in your town you can find them at a relatively good price online.
I've always been fond of hematite as a stone that aids in calming and grounding one. You could carry a single stone with you, or you can find hematite jewelry to wear to serve the same purpose. I have a hematite bracelet that I wear when I am feeling stressed.