I was just a little bit lazy (quick and easy, remember) and didn't want to get my fingers all sappy, so I grabbed my greens at the nursery. But you could just as easily trim your own backyard evergreens for what you need.
And don't forget, Home Depot and Lowes will often give you some Christmas tree cuttings if you ask them nicely.Or they may have pre-made bundles of mixed pine boughs for sale.
Fill a pot with soil. Or if you have a fall container planter still sitting around, you can prune the mums to the ground and use that to anchor your plants.