Trees, I have cut a rather large volume and found that horse people like it, as horses will not crib on Cottonwood. It is tooooo bitter for their tastes. Some furniture makers out here in Oregon have used it also. Many coffens are made of a species of Cottonwood, which I do not know. It is a very beautiful wood, that which I have sawn. i have some in the yard that range from 5' to 6' in diameter. Some are in the sizes you speek up also. for the horses I would cut a full 2" x 6" board for the added strength it provides. I would also suggest not cutting the lumber into very wide boards as this wood likes to cup and possibly twist with the thinner dimensions. If you cut 5/4 I would stay at a width of 8" or less.