Some do, some don't.
So called bullion gold and silver coins are minted by governments - American Eagles, Canadian Maple Leafs, UK Britannias, etc but they have no numismatic value, they are only worth their gold or silver content, despite what the ads in American Rifleman and other "conservative" publications suggest. Then there are "restrikes", also minted by governments - Austrian 4 ducats, Hungarian 100 korunas, Mexican 50 peso, etc but they are not rare and also have no numismatic value.
American gold and silver coins minted before 1933 or 1964 MAY have numismatic value, depending on rarity and condition, but Chinese counterfeits have gotten very good and most "rarities" advertised in "conservative" magazines and on conservative websites are not rare and have a small value over metal content.
On the other hand, a 1793 chain cent, face value $0.01, was sold at auction in 2008 for $126,500.
Buying "collectible" coins is highly speculative and the market is riddled with fraud. Most people who play in that market are suckers. I've been a coin collector since I was ten and it's a great hobby but a foolish investment.
If you are thinking of buying bread with silver, use old US coins in circulated condition - but remember, once that becomes a necessity (if that ever happens), allowing even the baker to know you have silver can and probably will threaten your life and the lives of your loved ones before the sun goes down.
This is the major flaw with those who call themselves "preppers."
Sure, there's nothing wrong with being prepared for a hurricane or ice storm with several weeks worth of canned foods in your cupboards with plenty of candles and firewood.
However, I alway get a kick out of preppers preparing for a true SHTF situation where civilized society literally shuts down.
You do not want to be the guy with a generator and "lights on" in that situation. You will draw desperate lowlife to your home like a porch light draws moths on a hot, humid night.
Slapping a bar of gold on the counter for a loaf of bread in a SHTF situation will similarly ensure that you are followed home and targeted for a raid.
I don't care how much guns and ammunition you have stored up. In a SHTF situation, you will be overrun and quite possibly killed by marauders who will pick your place clean.
If you are a prepper, best keep a very low profile and don't brag about it to anybody. Not even family members.