I'm building a somewhat "pre-fab" shed.

The booklet says use packed 3-inches of 3/4-minus gravel and then
patio stones for the foundation -- pressure treated skids will rest on
the patio stones.

My question, and the guy at the local block and concrete place claims
not to know ??? what size patio stone do I use, apparently they come
in all sorts of 12"X12" or 12"X16" sizes, made of lots of pumice, not
so much pumice, more PSI, less PSI....all are cheap enough, $1 - $2 a
stone.....

So, for a 10-foot X 16-foot shed (cedar siding, inside lined with
plywood, Gable roof, the 16-foot is the length....anyone have any
recommendations on patio stone types....??