In autumn, when I was a kid, I used to drive with my dad through nearby rural towns collecting bittersweet. The vine grew wild along the sides of infrequently traveled roads, and we'd break out the clippers and snag some for home. My dad made a swag of it for our entryway, and we'd put shorter bits into vases he had inherited from my grandma (who also used to harvest bittersweet).
Bittersweet works well for wreaths and simple floral arrangements and blends perfectly into the orange-heavy Thanksgiving color scheme. The vine dries well, which means you can keep some natural color in your home even as the days get longer and darker.
While I love the look of bittersweet and the memories it calls up, it's important to know that all parts of the plant are poisonous if ingested (so be especially careful around kids and pets ). That said, it was never a problem in my family.
If you've thought about harvesting bittersweet, it is also critical to know to avoid the Asian variety (or burn it if you have and want to dispose of it). This harmful invasive variety chokes out other plant life; learn more from the USDA. If you still want the look, you can go to a responsible florist or buy artificial bittersweet from a craft store.
Images: 1. Garden Mama 2. Martha Stewart 3. Flickr user Postscript Love via Apartment Therapy 4. Faith Durand for Apartment Therapy 5. A plant similar to bittersweet on Saidos da Concha 6. Studio Choo via Pink Street Design 7. Better Homes and Gardens