These coins were minted for circulation in Southern Rhodesia, at the time a territory of the British Crown. The area roughly corresponds to modern-day Zimbabwe. Coins before 1948 show George V; after 1947 George VI.
While they can acquire some toning that is reminiscent of that found on silver coins, they were minted in copper-nickel, and have no bullion value.
However, they have a nice collectible value, especially when uncirculated. The bust of king is found on the obverse, and the reverse has a cool bird sculpture.
This what the catalogs have to say about these coins.
worn: $1 US dollar approximate catalog value
average circulated: $5
well preserved: $12
fully uncirculated: $30
Coins dated 1948 are common in average circulated condition, where they catalog around $1.50.
Coins dated 1950 are scarce; multiply the above values by 2.
Coins dated 1952 are scarce in well preserved and fully uncirculated condition; multiply the above values by 2 for coins dated 1952 of these grades.
Remember to check out the 'Important Terminology' page on the left side in order to properly interpret these catalog values.