Flag of Milford in Nebraska, created according to File:Flag of Milford, NE.png. It seems that the uploader is the flag's creator, Nolan Eickhoff, so it has been released as CC BY SA 4.0. Though,  it seems that it meets the requirements for PD-shape. As FOTW notes, "According to Eickhoff, the white symbolizes peace, the black justice, the grey bravery, the purple kindness and the gold prosperity. The shape of the lines represents Milford moving forward, as it resembles an arrow pointing toward the future. The mill wheel is for the old mill that the town is named after, and the wheat is for the agriculture the town is based on."
Own work
Nolan Eickhoff (original); vectorization by Flagvisioner