Anything you can come across will be money in the bank. Just don't steal it. lol
But the most things for scrap that bring a good profit are copper, brass and aluminum.
Aluminum cans bring some money too it just takes awhile to get enough saved to make the trip to the yard worthwhile.
I'm a part time scrap metal recycle'r and I scrap anything I can. I haul off old appliances and any junk for people for free.
I currently just sell Aluminum cans, unclean copper, and unclean aluminum.
The clean aluminum, tin, Iron, clean copper etc I'm saving to sell in the future once prices rise again.
I have the space to store 500 Tons or more of scrap tin and Iron so I can sit on that as long as I have room to store it.
The clean copper I just keep in buckets, and the aluminum in barrels. Also saving ac copper/aluminum radiators for awhile until I save enough to make the trip worthwhile and the prices go up.
Those ac copper/aluminum radiators from window ac's can bring some good money if you have enough of them.
I had around 10 of the ac/ copper aluminum radiators that I had to sell last year and I got near $60.00 for them.