Around here, I'd say raised beds are the way to go when growing veggies. I've also seen brambles planted in raised "mounds" forming hedgerows like you mentioned, but above ground. Obviously, this is done to avoid the need to dig down into the clay (which is reason enough), but also provides the plants with the well drained soils they need. Sometimes that clay acts like a preverbial clay pot without a drainhole.

Good luck!!
Shannon

I also live on old farmland here in Butler County. We have a huge veggie garden and lots of flowers. I have no raised beds. We rototill in lots of compost every spring and that seems to do the trick. Don't have any problems with drainage.

Clay is a pain in the neck to work with for the first few years. Once you've gotten some compost into it, it is much easier.

Diane