The 1883 Half-Sovereign has a crowned shield on the reverse. The mintmark, if one exists, will be below the shield.
Royal Mint London - no mintmark
Melbourne Mint - "M" below the shield
Sydney Mint - "S" below the shield
All British Pennies from 1883 to 1911 inclusive have no mintmark. They were all minted at the Royal Mint London.
There is no mintmark on the 1921 British Penny, they were all minted at the Royal Mint London.
No British Queen Victoria Penny minted from 1883 to 1901 inclusive has a mintmark. During this period, Y was not a mintmark used on British coins. If the "Y" looks like it has been added after the minting of the coin, it may have been added by a group trying to bring notice to a cause. Around this time it was not uncommon to see a "W" stamped into some coins. The "W" standing for "Women's Suffrage", a popular cause at the time.
There were about 10,041,000 British 1904 Sovereigns minted at the Royal Mint London (no mintmark). There were about 3,743,000 British 1904 Sovereigns minted at the Melbourne Mint (mintmark = M to the right of the date). There were about 4,506,000 British 1904 Sovereigns minted at the Perth Mint (mintmark = P to the right of the date). There were about 2,986,000 British 1904 Sovereigns minted at the Sydney Mint (mintmark = S to the right of the date).
Assuming the coin is circulated and has no mintmark, the 1883 Morgan dollar is a very common coin with retail values of $32.00-$39.00 depending on the grade of the coin.
British 1875 Farthings minted at the Royal Mint (no mintmark) - 712,760 minted. British 1875 Farthings minted at the Heaton Mint (mintmark = H) - 6,092,800 minted.
Assuming the coin is circulated and has no mintmark, the 1883 Morgan dollar is a very common coin with retail values of $31.00-$39.00 depending on the grade of the coin.
There were 22,380,000 1910 Sovereigns minted at the Royal Mint London (no mintmark), plus a possible further 10 million minted at the Melbourne, Perth and Sydney Mints (mintmarks M, P and S respectively).
1883 Morgan dollars are very common, uncirculated coins with no mintmark sell for $50.00-$65.00. The actual value depends on the grade of the coin.
Assuming the coin is circulated and has no mintmark's, retail values are $29.00-$40.00 depending on the actual grade of the coin. The 1883 Morgan dollar is a very common coin.
British 1875 Pennies were minted at either the Royal Mint London, or the Heaton Mint in Birmingham. The Royal Mint Pennies have no mintmark. The Pennies minted at Heaton have a small "H" below the date on the reverse. All British Pennies minted at Heaton from 1874 to 1882 inclusive will have the same mintmark in the same place.
If there is a mintmark at all, it will be a very small "H" to the left of the date in the exergue. The "H" indicates it was minted at Heaton in Birmingham. All 1912 Pennies without a mintmark were minted at the Royal Mint.