I was looking out the upstairs window, and noticed a beautiful male Goldfinch. He swooped down from a perch and landed on a flowering Lyre-leaf sage, bending it way down, then proceeded to peck and the stalk. I assumed he was eating the seeds. I've never seen them do that before, so I was fascinated. I then noticed the more drab olive-colored female was already on another sage flowerstalk, also busy pecking away. I thought "neat!" since Lyre-leaf sage, a native wildflower, is just starting to flower beautifully, and I had transplanted some of the abundantly self-seeding new plants around the garden.
Then I saw another male Goldfinch. It was on the arch trellis to the old Sunflower House -- typical cautious scouting behavior before doing something. I thought he was going to a different clump of Lyre-leaf sage, but, instead, he hopped down to the Broadbeans -- the same ones that are getting massive attack of black aphids. He landed on the one on which I saw the Aphidiid wasp, which is so raggedy looking at the top that I was thinking of calling it a "necessary casualty." Now, he's picking between the shriveled leaves on top of the Broadbean. Now I KNOW there's nothing there but those (presumably parasitized) black aphids.
... then the light dawned I bet your finches were also going after aphids on your Swiss Chard!
Goldfinches as well as House Finches, Chickadees, and Titmice will also swarm all over the Golden Honey Locust and Plum trees in spring when they're aphid infested.