All previous outside structures have built, three sheds one cabin,
large wooden deck etc. we have dug down and used posts (stubs of
telephone poles and similar.

Now wondering if possible to build a shed on those concrete blocks
that just about sit on the surface. The blocks probably weigh 50 lbs
each, and are shaped on top to fit four by four post or cross member.

They are sometimes used here to support a deck or patio.

Considering a simple wood frame shed approx. 12 by 20 sitting on nine
of those blocks, about six inches to one foot off the ground, with
possibly an insulation pad below each block to slow freezing and
heaving of the ground.

Advice/comment welcomed.