I think I now know what that crown is. It's the FŽanorean Idiot Ball
Original quote:But even in the hour of the death of FŽanor an embassy came to his sons from Morgoth, acknowledging defeat, and offering terms, even to the surrender of a Silmaril. Then Maedhros the tall, the eldest son, persuaded his brothers to feign to treat with Morgoth, and to meet his emissaries at the place appointed; but the Noldor had as little thought of faith as had he. Wherefore each embassy came with greater force than was agreed; but Morgoth sent the more, and there were Balrogs. Maedhros was ambushed, and all his company were slain; but he himself was taken alive by the command of Morgoth, and brought to Angband.