Looking for Portable Aromatherapy Options

I’ve known that smelling scents is a good grounding technique for me, but today it came in clutch while driving. I started panicking but smelled a brownie I had with me and immediately calmed down. Unfortunately keeping a brownie on me at all times isn’t practical. What are good ways to keep any sort of aromatherapy tools on hand? I typically have a backpack with me so anything that fits in there would work great for me.