Creeping sedum groundcover (stonecrop). Not evergreen but has nice color and will bloom yellow flowers.

Vinca minor has nice blue flowers. Stays green.

@suzy jackson Libertia peregrinans is nice looking but I wonder if the tall inverted pyramid shape of the grass would compete with a similar shape on the Kangaroo Paws

I would agree that there will not be a huge difference in architecture...but in a small, formal space like your bed, I would definitely try to avoid that 'bedding out' look of alternating tall and short plants. My inclination would be to have complementary rather than contrasting plants because there is already a defined shape and structure to the existing bed (iyswim). I also kinda like the idea of growing plants from a similar region (New Zealand/Australia) together...hence coprosma and acaena buchananii (bidibid).

Search for Myoporum parvifolium or Viola hederacea .

@shaxhome (Frog Rock, Australia 9b) I love Myoporum parvifolium. It reminds me of Creeping Phlox from a distance (not close up).