Mahalaya Amavasya - Pinda Pradhanam

M ahalaya Amavasya or Sarva Pitru Amavasya is considered extremely important and highly sacred. Sarva Pitru Amavasya is intended for all ancestors, irrespective of the lunar day they died. It is the most important day of the Pitru Paksha. Those who have missed performing shraddha for any unavoidable reason can do so on this day. A shraddha ritual performed on this day is considered as fruitful as one conducted in the holy city of Gaya, which is considered as a special place to perform these rites.

Do Pitrus come in the form of crows on the day of Shraddha?

In Uttara Ramayanam there is a story about the crow's right to eat the offering of rice to pitrus. Once a king named Marutta performed a Mahesvara sattra. Indra and other gods attended the sattra. Hearing about this, Ravana came that way. The frightened gods took the forms of different birds. 

Valmiki Ramayana, Book 7, Chapter 18, Verse 5:

इन्द्रॊ मयूरः संवृत्तॊ धर्मराजस तु वायसः
कृकलासॊ धनाध्यक्षॊ हंसॊ वै वरुणॊ ऽभवत

indro mayūraḥ saṃvṛtto dharmarājas tu vāyasaḥ
kṛkalāso dhanādhyakṣo haṃso vai varuṇo 'bhavat

Indra took the form of Peacock. Yama escaped the attention in the form of a Crow. Kubera took the form of Chameleon. Varuna took the form of Royal Swan. From that time, Yama was pleased with crows.

Valmiki Ramayana, Book 7, Chapter 18, Verse 26: 

ये च मद्विषयस्थास तु मानवाः कषुधयार्दिताः

तवयि भुक्ते तु तृप्तास ते भविष्यन्ति सबान्धवाः

ye ca madviṣayasthās tu mānavāḥ kṣudhayārditāḥ

tvayi bhukte tu tṛptās te bhaviṣyanti sabāndhavāḥ

When human beings suffering from hunger, if you are fed/eating, those people become happy as if they have (met and fed) all his relatives (past and present). 

He gave a blessing that in future, when human beings worship the pitrus by offering pinda pradhanam (cooked rice balls with black sesame seed) to them, the crows will have the right to eat that rice. Thus the right of the crows to eat offerings of pinda pradhanam, originated from that time.

True benefit is only achieved through performing shraddha with homam! Only when performed with homam, these are given thrice to the parents - first through the agni swaroopam, then through the brahmana bhojanam and then lastly through the pinda pradhanam. Only on doing these three steps, then the remainder cooked rice becomes pitru sesham. Hiranya shraddha is told for people who have got certain limitations like very aged and not able to perform the long procedure shraddha etc. All capacitate (it is not financial alone but physical and mental too) people should perform shraddha with homam.

Courtesy:

http://www.sacred-texts.com/hin/rys/rys7018.htm
https://in.answers.yahoo.com/question/index?qid=20110406002926AAXlyC2
https://www.trsiyengar.com/id139.shtml