Is there any story that a son of Indra in the form of a crow was punished by lord Rama with his Brahmastra? I always listen to it.
This story is mentioned in Sundara Kanda Sarga 68. Sri Rama punishes Jayanta, son of Indra who was in a disguise of a crow.
It was narrated by Seetha to Hanuman as a token of remembrance. This happened when Sri Rama and Seetha were in forests in Chitrakuta mountain. Hanuman asks for a token of remembrance ans Seetha narrates a story .
Hearing Hanuma's words, Seetha like the daughter of a god, slowly spoke the following words, strung together with alphabets of tears: "You tell this (following) excellent thing as a token of remembrance to my beloved husband." [Sundara Kanda 38.11]
One day, Sri Rama and Seetha went for a leisure walk. Then a crow yearning for meat started pecking Seetha devi continuously. Seetha devi resisted by picking up a clod of earth. The incident made her uncomfortable. Sri Rama laughed at her. After that, Seetha devi took shelter of Rama and slept in the lap of Sri Rama. After sometime, Sri Rama slept in the arms of Seetha Devi.
Then the same crow appeared there all of a sudden. It again started pecking and annoying Seetha devi. It started to peck the meat in the bosom region of Seetha Devi. Drops of blood fell on Rama's face. By this Sri Rama said the following words.
O Seetha the round-thighed woman! Who has wounded the space between your breasts? who is playing with a fire-faced serpent filled with fury? [Sundara Kanda 38.26]
and took a glance around to know who harmed Seetha Devi. He found a crow with claws moistened with the blood of Seetha. That crow was Jayanta, son of Indra. Sri Rama swirling in his eyes in anger decided what to do in the matter of crow. He picked up a blade of grass (kusha) and employed Brahmastra unto it and released it unto the crow (All cannot employ divyastras unto blades of grass. It was possible because Rama had the knowledge of ऐषीकास्त्र(aiṣīkāstra). Ashvatthama also used this astra to release Brahmashirastra in the Mahabharata).
That crow (Jayanta) went everywhere to save himself including his father Indra but none could save him. He finally returned to Sri Rama and took the refugee of him.
That Rama, who affords protection, was compassionate and protected that crow, which fell on the ground (in salutation to Rama) and sought for protection, eventhough it was apt to be killed. [Sundara Kanda 38.34]
Seeing that crow, coming exhausted and dejected, Rama said to it: 'It is not possible to make Brahma missile a waste. For this reason, tell me what to do now. [Sundara kanda 38.35]
Then the crow replied that the brahmastra can take its right eye. That great missile took the right eye of the crow. The crow after saluting Sri Rama and Dasharatha left to its own abode. This is crow is referred to as Kakasura.