Steve, we do have trees (white oak) available to us at Constitution Grove. They are even GPS tagged so we can find them quickly and easily. We have another grove in Kings Bay, Georgia for live oak.
The problem is time and cost. To harvest them and process them just takes too long and costs too much. A 24 inch diameter tree will only yeild a single hull plank and it needs to be clear and straight for over 40 feet!
The last time trees from the grove were used was in the early 90's during the last major restoration. Because of difficulties experienced during that, it was decided that all major components would be made from laminates in the future.
The company we now use is awesome and they can meet all of the military specifications we put on the materials. Also, the way we have the laminates constructed also minimizes the possibility that you can tell they are laminates.
Be well,
Doc