jack sobon's "timberframe construction -all about post and beam building" has a great photo and some writing about dry laid stone.
In my work at our local museum I built several of these foundations, and replaced "railroad tie" foundations with dry laid stone foundations.... for small or medium sized buildings, I feel dry laid stone makes an excellent foundation.
As far as material goes, stone or block that has two flat sides is easiest to build with. Flat limestone is the first thing I would look for. Try searching the internet for "dry laid stone"....
