Hi all

I recently came across the following reply in an (American) play:

'Beaty don't know nothing! Hills of beans have flags in them
 announcing what Beaty knows!'


Beaty being a particularly stupid character in the play.  I know that
"hill of beans" means something like "nothing at all" or "worthless",
but I was wondering about the "flags" on them - do they make the
insult worse in any way?  Or am I completely mistaken about the
meaning of this idiom?

Grateful for any hints.

Cordially

Joachim