Question
We just had a large oak tree felled as after all attempts by our arborist to save it was to  no avail. The circumference was over 6 feet and we found the center to be hollow...a radius of about 2 feet. What can we do   to "fill" it so that we can make a planter for the top...we do not want to grind it as the roots provide beautiful edible mushrooms this time of year and we hate to risk losing those as they grow along the root system. Can we put sawdust or shavings inside? many thanks for any help or suggestions!

Answer
Sounds like a good idea! I would try and get as much of the rotting wood out of the stump and then fill it with potting soil. Then you can plant what ever type of plant you want in it. IF it hold water you can drill a couple of hole  on either side low on the stump to drain the excess water out.