I mix whole shelled sunflower seed into what goes in the feeders. In wet weather I watch how much of this I put out, since it spoils so quickly.
For American Goldfinches, it’s as attractive a food as the in-shell sunflower.

This American Goldfinch is.
A male American Goldfinch blends in quite nicely.
This male American Goldfinch in molt briefly perched on the shepherd’s crook before dropping down to the nyger seed feeder.
An American Goldfinch cracks open a sunflower seed on a recent -17C morning.
A male American Goldfinch.
. . . and a Pine Siskin.
Despite a day of freezing rain, sleet, and rain, four bathing Pine Siskins are joined by an American Goldfinch.