Stone soup is an old fable - but basically it's "whatever you have, find it and throw it in a pot and make do"
I've never actually made split pea soup before - but I have a giant hock bone from my pig last year and I've been dying to try it.
When my mom made it she grated a carrot in it and added a splash of Worcestershire sauce. It was good. Your hock will make it even better!