Go to your local Thrift shop or some other such venue and look around their shelves of nick knacks. Look at the metal trays and containers and even flower holders for a triangular mark on the bottom that indicates it's made of PEWTER. Pewter is mostly TIN/ANTIMONY with a bit of lead. They used to make dinner plates, decorative plates, cups, goblets, alcohol flasks and a multitude of other cast objects out of Pewter. Often large pieces weighing from a few ounces to a few pounds for less than a dollar per pound.
I picked up a flower vase that weighed just over two pounds at the local Salvation Army store for a dollar on Tuesday. Yes, I gave them five dollars and told them to keep the change. They pointed out a lot of other stuff but it was all stainless or silver plated brass. One easy way to tell if it's Pewter is to bend it. If it bends easily it's usually Pewter. You don't need a lot of pressure to bend Pewter products so don't try to pretend you're Hercules and bend up the stainless/silver.
Most of what I find is made up as beer steins. Some of it is beautifully cast or engraved and it's a shame to melt it down but after seeing so much of it I have become quite mercenary about slipping it into the melting pot. Most of it is personalized anyway.
Another good place to look is at scrap metal dealers. Often they have big balls of 50/50 tin/solder or bars of tin or if you are really lucky a big pile of Linotype. Linotype used to be easily come by but with new printing procedures and lack of printers purchasing the Lino letter/number blocks it's getting almost impossible to find. I picked up 200 pounds of Pewter and a hundred pounds of Linotype from a scrap dealer for $150 but I had to go to his yard to pick it up. His laborer had even melted it into 5 pound ingots for me. The dealer figured $150 was about what he would have cleared on it when he took it to a local smelter as scrap and I saved him the time and expense of sending someone to do it.
It was darn good stuff. According to my hardness tester it was almost pure tin/antimony. I am going to use some of it to cast up some 7mm bullets with gas checks to see how fast I can push them accurately without leading. Likely a pointless waste of good tin but interesting and fun to do.