You’re not going to build any large projects out of these scrap pieces of wood, but you can sure build an armload of jigs, fixtures, braces and any other small shop projects, including decorative shelves, picture frames, bird houses/feeders and lots of scroll saw patterns.
Scrap plywood, osb, flooring, dimension lumber and paneling can all be gleaned from building sites, if you ask the project manager in a gentlemanly fashion, and the same holds true for carpenter shops and furniture makers. Recycling sites sometimes have areas where scrap wood is piled and these can be picked over for wood treasures.
Pallets can be found almost anywhere goods are shipped. A word of caution here, stay away from pallets that have chemical stains, smell badly or are decaying. The last thing you need is sanding and planing dust from contaminated pallet wood in your lungs.
Demolition sites are another gold mine for wood scroungers, but don’t go poking around until the machinery has left and you have permission to do so. For the folks who like to work with barn board, get out and drive around the country and pound on doors. You will get nothing if you do not ask. I have had farmers glad that I was taking away their junk.
Happy wood hunting!