A pair of American Goldfinches at McInnish Park in Carrollton, Texas.
Wikipedia has this to say about American Goldfinches:
The American Goldfinch (Carduelis tristis), also known as the Eastern Goldfinch, is a small North American bird in the finch family. It is migratory, ranging from mid-Alberta to North Carolina during the breeding season, and from just south of the Canadian border to Mexico during the winter.
The only finch in its subfamily that undergoes a complete molt, the American Goldfinch displays sexual dimorphism in its coloration; the male is a vibrant yellow in the summer and an olive color during the winter months, while the female is a dull yellow-brown shade which brightens only slightly during the summer. The male displays brightly colored plumage during the breeding season to attract a mate.