Does there exist a machine that I can rent at the end of the summer that I can dump everything into and it will grind it up to about a 3/8 "?
Stuff I will have to grind up is leaves grass clippings tree limbs trees sticks shrubs dead stuff etc...
We bought a Morbark 1000 earlier this year. It is awesome for reducing the brush and logs down into mulch. We primary grind to 6" and then run the material (usually some time later) back through 1" and 1 1/2" screens for a finished product we call outback mulch or ecomulch.
Do yourself a favor and keep the leaves and grass separated from the logs and brush. The logs and brush are pretty easy to run through. Sometimes we bring in a bigger grinder if the piles get too big. It has its own grapple to load the tub. We load ours with an excavator and a thumb. Also, keep the stumps with rocks in a separate pile (they can be split apart for grinding later). The stumps might have rocks which will trash the hammers and cost you big bucks whether you rent or own the tub. The leaves and grass will compost by themselves with some flipping (aerating).
Here is a picture of us working with the grinder operator to load a 1300. I am in the excavator picking through the stump pile. After all the logs and stumps are picked out we let the small sticks and debris rot and compost with the leaves there are too many problems running the gritty stuff through the tub. In the big log picture, that is about the limit of size you can fit in the tub. It was too much for the grapple to make the full lift, but the excavator handled it ok.