Gall had the radial ray structure of all normal galls, but maggot chamber was at edge only. Thus the central chamber may not be reason for the radial design of galls. 10 - no holes, 2.1 x 3 cm gall. It had been rainy misty weather for 3 days. Galls were easily cut with sharp knife.
Dry galls can be very hard to cut.
Thus if maggot in center, I would not cut it. Web search via AltaVista goldenrod gall fly . ACornell University essay on plant galls. Kelleher, M.J., Rickards, J. and Storey, K.B. 1987. Laboratory investigations of temperature cues in the regulation of cold hardiness.