They are 'natural items' we collect on our travels (e.g., pinecones, sand, rocks). We put them in IKEA jars and label. I have them proudly displayed on my fireplace mantle. One of my favorites is Volcano Ash from Mount St. Helens in Washington; we all kept a lookout while Scott scooped some up just inches from one of the nearly million signs saying "Do Not Take Volcano Ash".