godot/scene/resources/default_theme/graph_port.svg

<svg height="10" width="10" viewBox="0 0 10 10" xmlns="http://www.w3.org/2000/svg"><circle cx="5" cy="5" r="5" fill="#fff"/><circle cx="5" cy="5" r="3.667" fill="#b2b2b2" fill-opacity=".65"/></svg>