Hi Cheryl, You can look around in your area for any custom sawmills. The Extension Forestry program in Oklahoma would be a good place to ask for this information (
https://extension.okstate.edu/programs/forestry/). I will say that it may be difficult to find a buyer for a single tree, especially a yard tree, so you might have to end up paying someone to take it down. That all depends on the relative distance a potential buyer has to travel and the quality of the wood.