Generally, Eucalyptus acmenoides, Eucalyptus melliodora, Eucalyptus moluccana, or Eucalyptus rummeryi, all of the family Myrtaceae
I have only found images of this Australian wood as a burl but because it is rarely available in the USA I have not made much of a search, so would not be at all surprized if it is available in lumber form in Australia. Although I list the name form with no space, it is more commonly shown as "yellow box".
my samples: NOTE: these pics were all taken in very bright incandescent lighting --- colors will vary under other lighting conditions
knife scale burl pairs from the same vendor
scales listed as yellowbox burl, but I see no sign of burl --- looks like crotch wood to me.
burl turning sticks
burl pen blanks
burl pen turning blanks that have been oiled and waxed