Scott
As George said, where you are makes a lot of difference to advice we can offer, If you are just looking for practice wood then buying a lot of expensive blanks is probably not the best idea, but you can turn something out of just about anything and probably learn a lot more due to needing imagination on where to cut etc.
In those days when we used to go out, we had a favourite country pub / restaurant that had a log fire, outside was a large stack of firewood I made a habit of pinching a piece of that wood on every visit, then I would turn something from it and return that to the wood pile on my next visit.
We are on one of those neighbourhood social media sites, often see posts of felled garden trees free to collector on there, will need a bit of drying time, but if you rough cut it that can be reduced quite drastically (clean up your tools after rough cutting wet wood!)
