What to do with all this stone?

When cleaning out all the groundcover from the upper patio and wall, I came across a small pile of stone right along the property line. After finishing the plantings on the upper patio, I decided to see how much stone was underneath the groundcover. Well, the stone pile never ended, I just kept finding more and more. So, I needed to find a purpose for all this stone. I knew I wanted to plant some Rhododendrons and Azaleas and with so much clay in my back yard, I thought I could build some fieldstone walls and backfill with great soil so I could indeed plant the plants I wanted. Here is a photo of the largest of 3 walls I built around the property. The other one is on the north property line that hides some old piping from the neighbors house and the other is in the most wooded portion of the yard and will be along the future "woodland" path. I had never built walls with natural stone like this, but I think they turned out really well and very solid. It was like putting together a puzzle with very large and heavy pieces.