In the early 19th century the governments of the British colonies Prince Edward Island and New South Wales used which widespread silver coins to produce their first own currency?

The used the Spanish dollar, the piece of eight ("Real de a ocho"), and punched out the middle part, thus creating two pieces: the middle part (which had been punched out) was called "the plug" and the remaining outer ring was called a "holey dollar".

The reason for this was simply shortage of coins in P.E.I.: The Spanish dollar was in circulation all over Eastern Canada but the value differed from region to region albeit the same coins were used everywhere. So merchants from P.E.I. sent their coins to Halifax to take advantage of the higher rates in Nova Scotia. The resulting shortage of money in P.E.I. prompted the governor in 1813 to gather in all the Spanish dollars he could and have their centres punched out. The plug was given a nominal value of one shilling and the outer part a value of five shillings - the combined value of the two parts was thereafter 20 percent greater in P.E.I. than outside the island which made it no longer profitable to send the coins to other parts of North America.

New South Wales had a similar problem by that time. Most of the coins left the colony through trade with visiting merchant ships so NSW ran into the problem of a lack of coinage which was solved in the same way as in P.E.I. The dump was valued at 15 pence (1 shilling and 3 pence) and the holey dollar at five shillings. The combined nominal value of the holey dollar and the dump (6 shillings and 3 pence) was 25 percent higher than the value of a Spanish dollar. Again: this made it unprofitable to export the coins from the colony.

https://en.wikipedia.org/wiki/Holey_dollar