Jeff,

Yes, there are a number of dwarf bronze flaxes, although I'm not sure how many are available outside of New Zealand, and they generally larger than 18".
Try these Phormium cultivars to start with - they are meant to grow no more than 1 m in height (about 40") (although in my experience, they nearly always grow double what is on the growers labels, unless restrained in pots!):

'Bronze Baby'
'Chocolate Fingers'
'Jack Spratt'
'Thumbelina'
'Tom Thumb'(not entirely bronze - green with a bronze edge)

As for other suggestions, (if you want a N.Z native) try some of the Carexs, or even Arthropodium candidum - it forms small clumps, with leaves growing to about 30 cm long and looks fantastic, especially with its white flowers. Unfortunately, slugs and snails love it too! Not sure if the Arthropodium would grow in your climate, but Carex should though - it's a tough plant once established.

Thanks Greenfingers. It appears Jack Spratt or Tom Thumb might work well. I found a great web site of a large local wholesale grower describing these and indicating they are in season and available. IÂll check a few of the nurseries in my area that they sell to.

Here is a link that might be useful: San Marcos Growers