Try your local tree surgeons, they have any amount of wood (admittedly a lot of it is not exactly construction grade clean straight and knot free.....but you might just get lucky
). A lot gets chipped, see if you can arrange with them to get there first You will find it much easier to cut and shape the wood if its still green and fresh. An adze might not be the easiest tool to do the job with. Maybe consider a normal axe to get the basic shape (from a split out quarter or eighth of ash or aok), then a knife (or better still a drawknife), maybe a spokeshave if you want a very fine finish. You could steam the wood to make it temporily pliable, to straighten it if it has minor bends. Steaming will assist the drying process. If you use a split section dont forget to cut the pithy section away from where the centre of the log was. Hazel is also a good bet, the sticks are already round but it takes time to dry them out.
