Re: Question: Different English names for "picnic cloth"

The thing you spread on the ground to sit on at a picnic is a
"[picnic] blanket", regardless of its actual nature.

IML "cloth" is usually a mass noun but unobjectionable as a count
noun.  It's just . . . vague.  I would almost never say "some cloths"
because I would have access to a more specific word (e.g. washcloths);
 if I didn't, that would most likely imply that they had stopped being
"cloths" and started being "rags". :)