The only Crown (Five Shilling) coins minted in Australia were the 1937 and 1938 Crowns which were round.
The only square coins minted in Australia were copper/nickel coins of Halfpenny and Penny denominations in 1919, 1920 and 1921 as trial patterns and were never put into circulation. They all featured a kookaburra on the reverse.
The 1919 Australian Shilling was not issued into general circulation and was a "pattern" strike only. An Australian 1919 sterling silver Shilling (George V)(Proof), uncirculated and in absolute mint condition could fetch up to $400,000 AUD. A reputable coin dealer will be able to give a more accurate valuation.
An Australian 1928 sterling silver Shilling (KG V), uncirculated and in absolute mint condition could fetch up to $3,150 AUD. If it has been circulated but still in good condition, it might fetch anything from $15 to $575 AUD. There were 0.664 million minted. An Australian 1928 sterling silver Shilling (KG V)(Proof), uncirculated and in absolute mint condition could fetch up to $90,000 AUD. A reputable coin dealer will be able to give a more accurate valuation.
An Australian 1959 50% silver Shilling (Elizabeth II), uncirculated and in absolute mint condition could fetch up to $30 AUD. If it has been circulated but still in good condition, it might fetch anything from $2.50 to £7 AUD. There were 10.156 million minted. An Australian 1959 50% silver Shilling (Elizabeth II)(Proof), uncirculated and in absolute mint condition could fetch up to $30 AUD. There were 1,506 minted. A reputable coin dealer will be able to give a more accurate valuation.
An Australian 1962 50% silver Shilling (Elizabeth II), uncirculated and in absolute mint condition could fetch up to $17 AUD. If it has been circulated but still in good condition, it might fetch anything from $2.50 to $5 AUD. There were 6.592 million minted. An Australian 1962 50% silver Shilling (Elizabeth II)(Proof), uncirculated and in absolute mint condition could fetch up to $375 AUD. There were 2,016 minted. A reputable coin dealer will be able to give a more accurate valuation.
An Australian 1963 50% silver Shilling (Elizabeth II), uncirculated and in absolute mint condition could fetch up to $11 AUD. If it has been circulated but still in good condition, it might fetch anything from $2.50 to $5 AUD. There were 10.072 million minted. An Australian 1963 50% silver Shilling (Elizabeth II)(Proof), uncirculated and in absolute mint condition could fetch up to $225 AUD. There were 5,042 minted. A reputable coin dealer will be able to give a more accurate valuation.
An Australian 1956 50% silver Shilling (Elizabeth II), uncirculated and in absolute mint condition could fetch up to $135 AUD. If it has been circulated but still in good condition, it might fetch anything from $2.50 to $25 AUD. There were 6.064 million minted. An Australian 1956 50% silver Shilling (Elizabeth II)(Proof), uncirculated and in absolute mint condition could fetch up to $385 AUD. There were 1,500 minted. A reputable coin dealer will be able to give a more accurate valuation.
An Australian 1963 50% silver Shilling (Elizabeth II), uncirculated and in absolute mint condition could fetch up to $11 AUD. If it has been circulated but still in good condition, it might fetch anything from $2.50 to $5 AUD. There were 10.072 million minted. An Australian 1963 50% silver Shilling (Elizabeth II)(Proof), uncirculated and in absolute mint condition could fetch up to $225 AUD. There were 5,042 minted. A reputable coin dealer will be able to give a more accurate valuation.
The Australian Kookaburra series of Proof and Specimen coins first issued by the Perth Mint in 1990, at 99.99% silver, are as close to pure silver as you are ever likely to get in a coin.
An Australian 1926 Shilling, uncirculated and in absolute mint condition could fetch up to $550 AUD. If it has been rattling around in somebody's pocket but still in good condition, it might fetch up to $5 AUD. There were 2.35 million minted. A reputable coin dealer will be able to give a more accurate valuation.
An Australian 1938 Shilling, uncirculated and in absolute mint condition could fetch up to $170 AUD. If it has been rattling around in somebody's pocket but still in good condition, it might fetch anything from $5 to $40 AUD. An Australian 1938 Shilling (Proof), uncirculated and in absolute mint condition could fetch up to $20,000 AUD. There were 1.484 million minted. A reputable coin dealer will be able to give a more accurate valuation.
An Australian 1915 sterling silver Shilling (George V)(minted in London - no mintmark), uncirculated and in absolute mint condition could fetch up to $7,750 AUD. If it has been circulated but still in good condition, it might fetch anything from $60 up to $1,600 AUD. There were 800,000 minted. An Australian 1915 sterling silver Shilling (George V)(minted at Heaton - mintmark = H below date), uncirculated and in absolute mint condition could fetch up to $14,500 AUD. If it has been circulated but still in good condition, it might fetch anything from $70 to $2,100 AUD. There were 500,000 minted. An Australian 1915 sterling silver Shilling (George V)(Proof)(minted at Heaton - mintmark = H below date), uncirculated and in absolute mint condition could fetch up to $180,000 AUD. A reputable coin dealer will be able to give a more accurate valuation.
There were only two years when an Australian Crown (Five Shilling) coins was minted, being 1937 and 1938. If by "polished die" you mean a "Proof" coin, both the 1937 and 1938 coins were minted as Proof and general circulation coins.