Also, after being 'liberated' there is a worrying chance of the tree dying. Trees in the wild push down massive roots, sometimes very deep, so you can increase the chances of its survival by severing roots a distance around the tree a year or more before you finally collect it.
Anything you purchase in a pot is already accustomed to a small root system, but then probably doesn't have a wide trunk even after years of growth. The compromise is to get a young bonsai or prebonsai and plant it in your garden or wherever. And here's the magic bit: plant it on top of a ceramic tile so that all the roots are forced to grow out horizontally before they can grow downwards. Like that, the roots are much easier to train back into a small pot, and you'll have a chunky trunk with lovely root flare at the base.
