We have a a friend who has access to free barn wood, so my husband pulled out a bunch of boards and cut them into roughly 5x7 pieces.
I made a little pattern for the nail placement and we hammered in the nails for all 70 boards!
I bought small brad nails from Lowe's and a multi-pack of embroidery floss from Hobby Lobby (with my 40% off coupon!). The whole project ended up costing a little over $10 for 70 boards! A great, frugal project that is perfect for our theme and perfect for adding a little fall touch to our house.