I know of someone in Canada that has overwintered cordylines this way - bareroot, under bags of leaves - and they were potted up in the Spring and amazingly were still green. They rerooted in the pots and did great. I have thought of this also. I till my garden space up every Fall, and usually bury some pots with trees in them in the garden. You would have to lay plastic on the ground, and somehow make sure that moisture couldn't get into the pile. Hmmm... Still not sure if that's feasible in a zone 7a. That would be one huge pile of straw and bananas

!! I may try that with one pseudostem this year and see how it works. Thanks for the thoughts!
I am digging a long trench in the garden, and putting some hardy palms in pots in it. I'll fill it with pine straw, then cover with plastic. Just running out of space inside for stuff, and don't have a greenhouse (but I can still dream).