My first choice is always silver American Eagles. I have been using Provident Metals for years and they are very reliable; never a single order or shipment problem.
The Eagles contain one ounce of silver and are actual mint-issued coins of the US. So do Maple Leafs and Philharmonics, and they are also good choices.
https://www.providentmetals.com/silver-eagles/uncirculated-silver-eagles.html
Be sure to look at https://comparesilverprices.com/ to find the best source of silver for you. I keep that in a tab for quick reference.
Many people prefer silver bullion bars or rounds of one ounce size. They are a little cheaper than Eagles because they do not have a premium created by the expense of minting. I prefer the Eagles because they are difficult to counterfeit and you know they are a full ounce. They are also our most attractive coins, I think.
If Steem makes it to $300, the Eagles will be somewhere in that range, too, so we will both be very, very happy!
The Eagles take your money out of the financial system and unties it from the Dollar. Remember that as Important Rule Number One!
Avoid the proof coins and those of supposed "collectible" value because you are paying a heavy premium for someone's opinion of the value.
No SD box! The safest place you can find is at home with you...preferably in a hole in the ground. That is safer than a SD box and you can get to them when you need them, especially if the bank is closed. The classic answer is that "If you don't hold it, you don't own it."