Ive got a lumber yard that cranks out odd sizes ranging from 12 by 2's to 14 by 4's to 4x4's and anything in between. If its big and square I pick it. Doug fir, lumber yards hardly carry hardwood but there has been the odd cut pallet in there. Other times they use these stickers for lumber and they look to be some kind of ironwood, at least the workers say they are. About 1/2 inch thick inch wide and maybe 3 feet long. Collected a good bunch. The other source is some weird pallets that have 24'inch long 3x3's. They are often a poplar- cottonwood or yellow pine. Easy cut and stowed for the day I am burning them.