No silver. They are copper-nickel
I have a republic of Liberia coin as well, and the certificate that came with it states it is copper-nickel.
If it's silver, then at least $30.00
In 1993 the Republic of Liberia issued a Nolan Ryan 10 dollar silver proof coin. The value of this coin is about $15.
The book value is about 8 to 10 dollars in the Krause Standard Catalog of World Coins. The ten dollar version of the same coin has one once of silver so has the real value.
It is 1 troy oz of 999 fine silver. So its value is the current silver price for 1 troy oz. Depending on its condition there could be some additional numismatic value to collectors too. Current silver price as of this moment is $34.28 per troy oz of fine silver.
Liberia has produced at least 100 different Twenty Dollar coins since 1983 (mostly from about 1997 onward). The silver content varies by the issue, but the most seem to be either about 2/3 of a troy ounce or about 1 troy ounce.
This is not a US Mint coin. It was made in Liberia, the composition is copper-nickel and is not a US legal tender coin. It has no numismatic collectible value. It's worth only what you can get for it.
A $5 Liberia coin in actual face value of about 8 cents Canadian or about the same in US dollars. I just looked it up on a currancy rate site.
Currently, the Liberian Dollar is at 57:1 against the US Dollar. So, that crappy, foil covered $20 note, those hucksters at the National Collector's Mint are trying to pawn off, are worth about 31 cents, and you have to go to Liberia to cash it in. Nice. One could argue that the subject note should be worth its weight in silver which is approximately $18 per ounce (as of July 08)... unfortunately, they don't tell you how much it weighs. Furthermore, they state it is "struck in pure silver leaf" which seems to imply that it isn't solid silver, but silver-coated. Truly a fine specimen of dishonest and misleading advertising.
The Silver Dollar Plant has leaves covered in microscopic silver hairs, these hairs reflect the light the sun has to offer, originally found in South Africa these plants are used to extreme temperatures and these hairs are the key to their survival.
An 1879 "Silver Dollar" is a Morgan dollar.