There are many Australian coins that have been issued since their introduction in 1966.
All circulated coinage is produced by The Royal Australian Mint. There are 2 versions of the Queens effigy, one designed by Ian Rank-Broadley and one by Jody Clark. The reverse has been designed by Stuart Devlin. These comprise of the 5 cent, 10 cent, 20 cent, 50 cent, 1 Dollar and 2 Dollar Coins. For Collectors of these circulated coins, they look for errors and also small mintages of years produced. Examples of these are the 2000 $1 Mule, the 1966 20c Wavy Coin and the 2 headed 10 cent piece or a 5 cent Flamingo. A special mention to the 1966 Round 50 cent piece also with this coin being 80% in Silver it is worth much more than face value.
Commemorative Coins have been produced with different designs throughout the years to commemorate many events in history, people and celebrations. Examples of these are the 2016 50th Anniversary or the Decimal Currency, 2014, 2015, 2016, 2017, 2018 100 years of ANZAC $1 Coins, 2001 Federation State issues in twenty cent coins or the 2001 Sir Donald Bradman. You may find these in your change however most are attached to a card and produced specifically for collection. Examples are the 2015 $1 Red Poppy Coin and the 2009 Moon Landing, 2014 AIATSIS, or the 2015 ANZAC Remembered, 2016 ANZAC to Afghanistan.
Collectable Coins are produced by Mints worldwide. These Coins are issued with a Certificate of Authenticity (COA) describing the coin and specifications. Usually they are also given a collectable number. There are also the collectable carded coins that do not come with a COA but state a limited mintage. Most of these coins will have a Mintmark on the coin to show where the coin was minted. Some coins have a metal of aluminium bronze, silver, gold and also bi-metal. Example of these Collectable Coins are the sought after 2012 $2 Red Poppy Coloured Rememberance Day Coin, the 2013 $2 Coronation Coloured Coin, Treasures of Australia Series, Lunar Year of the Series.
No matter your interest you will be sure to find a coin on it.