i usually keep the stock bits until the day i sell the car.
but sometimes i get lazy and just sell the car and later I need to make space so i take it to this city run recycling center. last time i took some car parts (springs, door, hood, trunk lid, exhaust, etc) they weighed it and gave me like $10 for everything.
i gave it to the guy who helped me out as tip. i just wanted to clear out my storage area..and i know my garbage truck guy would never take big things on the edge of my driveway.