Hey Tom, where are you finding these fantastic pieces of driftwood? I'm going to be cave diving in the High Springs region in August, and would love to get away for a morning to see if I can find a few nice pieces for my own tank...
Try Tom's Cyress off of 301 in Waldo, cannot miss it.
He sells pretty much most things you might find.
Otherwise, nab what you can.
Go to Blue Hole in Ichetucknee, it's a good cave dive site. I did my reserch in that spring bowl.