Goldfinches eat seeds almost exclusively. Even this late in the winter, they come to the park to find seeds in the dried heads of composite flowers like teasel and burdock.
In their gardens, people often leave the dried heads of sunflowers standing through the winter as food for finches without realising that many other garden flowers would serve the same purpose: asters, yarrow, all kinds of marguerites and the long, shapely seed heads of buddleia. A flowerbed, gone to seed, is a valuable source of food for overwintering finches.
We are encouraged to cut down, tidy up and clear away when the flowering season is over. For the sake of our dwindling populations of seed eating birds, we should resist; an untidy garden is a wildlife haven.