I'm also new to turning. I've bought a few seasoned blanks but have mostly used green wood. Areas you might want to consider if you haven't already -
From friends.... Now that friends and family know that I am turning they are all great at providing little bits when friends of friends chop trees etc. Some chunks have been good and others ahve been fairly rotten and soft. However, I was recently able to purchase a bandsaw here on UKW, and after thinking I had run out of wood, I have been able to convert my scrap pile into lots of usable pieces.
From your travels... My greatest find was a large rotting log, as long as my car is wide and about 8 inches diameter, in a ditch at the road side on some public land. I still cannot identify the wood but once the moss was stripped off it was in great condition I still have it and just saw off lumps as and when I need it, and it hasn't cracked or split as it has dried. I've also driven past a few tree surgeons in action and they've all been happy to let me delve in to their trailers and grab a lump.
From freecycle... I don't know about your area, but there always seems to be lots of old furniture going on place like freecycle near me. I've read that boards can be cut down, and table legs re-turned etc. I haven't tried this though.
Hope this helps?!