Hi Jennifer:
It looks to me like you have the makins of one or more great raised hugelkultur style beds. The trick to using clay soil is to mix as much organic matter in as possible.
The rocks will make a great border (and give you some great muscles if you try to move them).
The wood will make a base for the bed and add organic matter to the soil. After that you can layer the clay, pine bark mulch, kitchen scraps. shredded paper, coffee grounds, leaves, and whatever (green) organic you can find to put in there. Come spring, you could add a few bags of top soil to plant in, or just plant in the amended clay.
I don't see that you would have to buy anything, except maybe some bags of topsoil, and some pine bark mulch and that would be optional.
Those are great rocks. Your neighbors should be happy to see your raised beds come next spring.
Here an idea for using clay in raised beds:
http://nestinstyle.com/garden/...
