In the field next door there was a pile of cottonwood branches from a tree they'd removed when clearing the lot a few months ago. (As I've noted, the owner wants $110,000 for a vacant double lot, when our single lot, with a house and garage on it, cost substantially less than that.) We had looked at those branches and decided that they included burnable-sized pieces. Lisa got out the electric chainsaw and a couple of long extension cords. There is a single power outlet on the west outside wall of the house, and we could reach the branches. I got kitted up and Lisa handed me ear protection, put hers on (and her safety glasses), and set to cutting the branches down to size.
Because we had the chainsaw out, we also cut down to burnable size the handful of oversize "fencepost" Douglas fir pieces. Every one of the pallets we bought had a few extra-length pieces used to hold the pallet together, and we had accumulated them until there were enough to justify cutting them up. With me feeding pieces and holding them, it took but a few minutes to produce another twenty or so pieces of usable firewood.
When we were finished in the field, we had another wheelbarrow load of usable cottonwood pieces for the wood box. Given the cost of firewood, we're happy to get what we can for the cost of merely our own labor.