I drive past a house with a large patch of Hollyhocks , and have noticed a lot of cardinals on the tall stalks. Can't see if they are eating bugs or seeds?

Cardinals eat mostly seeds unless they are feeding young and they will feed them bugs. So more than likely they are eating the seeds

I wish our cardinals would eat a few thousand of our hollyhock seeds.
Maybe I need to gather the seeds now and save them for winter feeding.

If they're eating hollyhock seeds, send them over here!