2020 One Dollar mule
On 11th November 2020, photos of a PCGS slab containing a 2020 Mob of Roos $1 reverse muled with a 10c obverse die were posted on a Facebook error coins group. The slab in question was https://www.pcgs.com/cert/40222602 and showed a 2020 Mob of Roos $1 reverse paired with a heavily clashed 10c obverse (part of the lyrebird are visible around the Queen's head) along with the tell-tale double rim on the obverse due to the slightly smaller size of the 10c die.
The mule was reported as having been discovered in a mint bag though the claim is unsubstantiated, and no other mules have been found in circulation to confirm this. The use of a heavily clashed die is curious too as the Royal Australian Mint generally has a low incidence of poor quality coins.
Currently there is only one known example of the 2020 $1 mule and there have not been any public sales yet.