I like to use old wood a lot and will harvest it from just about any source available ; pallets, barns, vegetable crates… you name it if its weathered and available, I want it. These two saws I use daily. The Skil saw is portable, very accurate and makes clean cuts in 3/4" boards up to 15" wide. I buy full sheets of plywood and have the store roughcut to 12"X48" (less than $1.00 for the cut). Then I can cut it to the size I need at home and cut around blemishes.
The other saw is a Ryobi oscillating tool. This is one of the handiest tools to own. Equipped with a carbide blade, you can quickly and cleanly harvest any board by cutting the nails or screws.