Hi Manny. I kind of expected a reply similar to this but I thought I'd float it in the ether anyhow.
I keep hearing the same thing... just dig up dirt. I think I finally get the idea!!
I have very clay-type soil around here, and lots of leftover grout from my DIY hearth pad that I plan to dump into the mix. I might give it a go this weekend.
Thanks for the reply! If nothing else, it reinforces the simplicity of making stuff.