How should I fill this big hole I found in my yard.

I live in a kinda urban area on a small half acre lot. I had a shed in the corner of my property that I removed. The previous owner had it on a 2 feet raised platform with blocks. I have a flooding issue in this part of the yard with all my neighbors grade higher than mine and bad drainage, I thought the shed was raised to keep it out of the water when it rains. Once I removed the shed and blocks I hit a layer of thin scrap metal like cooking sheets and oil drum lids. Under that was large rocks loosely stacked, no fill, some trash and a few bones. The rocks range in sized from baseball to basketball size. I pulled out most of the rocks and hit a clay layer so I think I reached the bottom. The hole is 6'x4'x4'. How should I fill this hole the right way to help with drainage? I'd like to put in a retaining wall along of the chicken wire fence and slope it down to the other corner of my yard so it can drain out to the road. How would you guys go about filling this hole, should I use a drywell that has an over flow I can run down slope?