This could have easily been a Pinterest fail. It turns out chopping down trees and neatly cutting them into equal pieces to fill your fake fireplace is really hard. That being said, it was so worth it. Don't attempt this alone though. You're going to need a man - make that anyone strong who doesn't mind getting dirty.
You will need:
Wood (nearby woods, firewood pile, etc.)
Saws (ALL OF THE SAWS - circular saw at the very least, chainsaw too if possible)
Rectangular Piece of Plywood
Clear Lacquer (optional)
STEP ONE: Cut down a bunch of trees (we needed three for more than 50 eight inch long logs). Cut the trees into logs of approximately even length. Measure the distance from the back of your fireplace to where you want them to stop, then subtract an inch or two (you'll see why in the next step). Optional but strongly recommended: spray the wood with clear lacquer and let sit for several days. There will be bugs. Once you're done here, the worst is over.
STEP TWO: Measure the length and width of your fireplace opening. Cut a thin piece of plywood to those dimensions. Exact measuring isn't that important here, but take note: you do not want it to be oversized. Spray paint the rectangle black. Place it in the fireplace hole, pushing it as far to the back as you can.
STEP THREE: Bring your lil' logs inside. Stack them neatly in the fireplace. Cry when you realize you're about eight logs short. Be okay with it because it still does a pretty good job "bringing the room together."