From Dave's Garden - "Pasopaya Palm, Bolivian Mountain Coconut Parajubaea torallyi
USDA Zone 9a: to -6.6 °C (20 °F)
From Wikipedia - Parajubaea torallyi, commonly known as the Palma De Pasobaya or Bolivian Mountain Coconut, is a species of evergreen flowering plant of genus Parajubaea in the Arecaceae family. It is endemic to Bolivia, where it grows in dry forest on steep rocky slopes at 2,400-3,400 meters altitude, and is now threatened by habitat loss. Mature plants can be over 13 meters in height. They can withstand temperatures of -13 degrees Celsius. The fruits, or cocos, grow 5-10cm in diameter in clusters weighing up to 15kg.
I have heard that is plant is growing in both California and Oregon states and that it should survive zone 8b. If I can ever find one and get it across the border you can be sure I am going to try it
FYI, someone is currently selling them on EBay, but I can not get it into Canada because it is coming from California.