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 ("soft white" at 2700K) 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