I found this and several other smaller pieces in a small creek less than 50 ft from my house 18 years ago. Sold the property since then, but would like to ask what type of tree and what age it could be. What would it sell for?
I am pretty sure this is NOT petrified wood. It looks more like fossil coral. Whenever people find something and they ask "what can I sell it for?" I pretty much answer the same thing: not much. Most common fossils are not worth anything but a few bucks and sadly your piece is no exception. I'd argue that you keep it on your desk or coffee table as a conversation piece. If you tell me what city you found it in, I can give you a date range.