A puzzling gift from California

My cousin Mary-Kay sent this Christmas present from California last year. I've saved it until now (I've been working on my Master's degree paper). With just a few minor edits to go on that, I have laid out the 500 or so pieces on Linda's art table so I can begin putting this challenge together this weekend. Once done, I may send it off to The Netherlands to a cousin who might be interested in putting it together. I will blip my progress over the coming week to reveal the subject.