I mainly collect silver US coins that are 90% silver, make in 1964 or prior. In 1965, the government took all the value out backing the money so this is why investing money in different places like metals and crypto's are essential. The Government knows when things hit the fan they can stand back and claim they couldn't do anything about it while they have their mansions and jets already on other islands if they ever need to get out of a place.
This is my favorite .999 Scottsdale Silver 2oz Round. It's the best looking round in silver that isn't much over spot. I either get US Eagles since they are backed by the Feds and almost no one fakes them. There will be highly sought out the day they stop making these. No other round stacks like it does and has an exact inverse on the underside. It really is an art round and $42 for 2oz is really good for what this is.
These 2oz rounds are actually stack-able. The back of each round has an imprint where any 2oz, 100g, or 5oz Scottsdale Silver Round so it really is a work of art.
Where to buy silver?
scottsdalesilver.com/store/product.php?productid=17562
providentmetals.com/silver/silver-coins.html
Tip: Almost never shop for precious metals on Amazon, almost everything is over priced and there isn't much supply/demand action or much for sale. Just make sure you see the amount of metal in whatever you are buying. Normally you will find 90% silver in older coins, .999% pure refined silver bars or rounds, or stainless silver that is .925%, just enough of harder additives to make the silver hard enough for use. Buying and saving silverware is a fun hobby. Many times people at auctions don't pay attention to what specific metal they have so you might find silver or somethings with copper, silver, brass, or even gold. Sometimes it's good to have "junk Silver" which are 90% silver US coins from 1964 and prior. Dimes could be worth $1-$2 in barter power. A roll of dimes is around $65 in silver right now.
American Eagles have a higher premium than something like a 10oz bar (below). But the US Eagle is often the only coins people collect. It's a great metal we need a lot more of and is useful so while it's at $16 now, it could easily go up 3-5x. Gold is great too but it has less of a chance of doubling since it's already so high just below $14k.
5 US Eagles for $100.47 for a special by AydinCoins
10oz Silver Bar Scottsdale Stacker Silver Bar .999 Silver $178
10oz Sunshine Bar for $187.50 on Ebay
100 Year Silver Chart macrotrends.net/1470/historical-silver-prices-100-year-chart
1912 Barber Half Dollar 
I hope to collect more metals, especially things like copper wires and other metals.
I will sometimes pick up metals. I even collect aluminum cans and a lot of random wires. Let me know if you have any, it might be worth me paying for you to send it! I like dozens of differing kinds and trying to collect every one I can from the periodic table of elements:
Oh, and also the 1964 and prior US silver, when our money actually was based one something in reality.
Coinflation has a great US Silver Coin Melt Calculator tool so you can see exactly the amount of money you have in silver from each coin - http://www.coinflation.com/silver_coin_values.html (and below is the one where you can calculate if you have a lot of them.
www.coinflation.com/coins/silver_coin_calculator.html