Mike wrote:

I'm putting in a 100 sq. ft. dry laid patio of flagstones. I've priced the
sand I'll need (2 inch foundation, 1 inch fine sand bed) at c. $220 incl.
$50 to have it delivered by truck. My question is, do I absolutely need the
foundation and bedding sand? Can't I just dig a shallow bed c. 1 in deep,
level it, lay the stones, and then fill in the cracks with a single 50 lb
bag of sand? I don't care if weeds and grass grow in the cracks.

I believe the base provides stability as the ground shifts over time. I
suspect with a 1 inch base, you're going to wind up with an uneven surface
within a few years.