We have Bunnings here in Oz which is a hardware chain. They now put all their timber and sometimes the odd metal pallets in the car park for people to take. Maybe they had too many people asking for them who had to climb over piles of supplies to get to them or the local tip charged too much.... don't really know.
Last week I went to get a couple of 2.4m long ones and got a 3.6m one too. Plus a pile of about 20 3X3's (75mm X 75mm) one metre long. Same as you Ace, got to find a project for them now.
Then I went around to the fencing shop to pick up some star pickets. They come in packs of about 500 then they sell them in lots of 10 or even individually. The packs are made out of 2 pieces of 2 inch angle iron with little chocks welded on them to make them stand squarely, placed at either end of the posts. Then there are four 500mm 7/8 inch bolts welded as uprights on all four corners which are threaded. An extra piece of angle iron is then bolted down on top at either end to hold every secure during transport. All this structure just goes to the tip when they are finished so I ended up with 6 of these structures. I am always looking for scrap steel.