How do you get good bonsai material?
There are two choices:
1) you start when you are young—very young, plant a tree and wait (It helps to believe in re-incarnation)
2) you go somewhere and dig up the gnarliest old little tree that you can find.
2b) ok you can buy something on e-bay.
Given that most of us are not that young any more we do a few club digs every year. Usually the dig is somewhere in the TX Prairie (or better what used to be the TX Prairie), at a farm that belongs to a club member (or a friend of a club member, or a friend of a friend …)
This year we dug up three hackberry trees. I must tell you, this is a lot of work. You are looking for a decent size trunk, nice movement and in general, tree material that can be trained into a bonsai over the next 5-20+ years.
Digging up one of these trees is a lot of work, in contrast to what one of our most experienced club members though, hackberry trees have a huge taproot right under the trunk. Digging up a nice rootball and removing enough soil that you can cut the tap root with a saw is quite a task, particularly since there there is a dense layer of limestones a few inches below the shallow top-soil.
Next order of business is to keep the trees alive.