Vishvedevas are the son of Dharma and Visva. They have performed great austerities to please Lord Brahma and got the boon to get the share of food in Shraaddha. This is described in Vayu Purana, Chapter 76.
दक्षस्य दुहिता ख्याता लोके विश्वेति नामतः।
विधिना सा तु धर्मज्ञ दत्ता धर्माय धर्मतः॥
तस्याः पुत्रा महात्मानो विश्वे देवा इति श्रुतिः॥ ३॥
Daksa's daughter became well-known in the world as “Visva' by name. By a ritual, O You knower of Dharma (Law), she was offered duly and righteously to Dharma. Her sons “ViSvedevas” were the great-souled ones. This is the traditional hearing.
प्रख्यातास्त्रिषु लोकेषु सर्वलोकनमस्कृताः।
समस्तास्ते महात्मानश्चेरुरुग्रं महत्तपः॥ ४॥
Well-known in the three worlds, they were offered obeisance to by the entire populace. All those were great-souled ones and Were performers of austere penance.
हिमवच्छिखरे रम्ये देवगन्धर्वसेविते।
सर्वाप्सरोभिश्चरितं देवगन्धर्वसेवितम्॥ ५॥
On the lovely peak of Himavan waited upon by Devas and Gandharvas, they moved about as such accompanied by all the Apsarsas and waited upon by Devas and Gandharvas.
महातेजा महादेवस्तपसा तैस्तु तापित:।
तपसा तेन सुप्रीतः कं कामं विदधामि वः॥८॥
Brahma spoke-- "Even highly radiant Mahadeva has been tormented by them by means of great austerity. I am well gratified by that penance. What desire of yours may I accomplish"?
एवमुक्तास्तदा विश्ले ब्रह्मणा लोककर्तृणा।
ऊचुस्ते सहिताः सर्वे ब्रह्माणं लोकभाविनम्॥९॥
This way addressed by Brahma, the creator of the world, all of them spoke out simultaneously to Brahma, the recogniser of the Universe.
श्राद्धेऽस्माकं भवेदंशो ह्येषे नः काड्क्षतो वरः।
प्रत्युवाच ततो ब्रह्मा तान्वै त्रिदिवपूजितान्॥ १०॥
"May there be a share of us in Srāddha. This
is a desired boon'. Replied then Brahma to those, who were adored in the heaven.
भविष्यत्येवमेवेति काङ्क्षतो वो वरस्तु यः।
पितृभिस्तु तथेत्युक्त्वा एवमेतन्न संशयः॥ ११॥
सहास्माभिस्तु वो भाव्यं यत्किचित्क्रियते त्विह।
अस्माकं कल्पिते श्राद्ध युष्मानग्रासनं ह वै॥ १२॥
भविष्यति मनुष्येषु सत्यमेतद्ब्रवीमि ते।
माल्यैर्गन्धैस्तथाऽन्नेन युष्मानाग्रेऽर्चयिष्यति॥ १३॥
“This way shall happen to be. This way the boon will be granted to you'. Pitrs then said
“All right', and continued, "there happened to be no doubt about it. Whatever is performed here shall be for you too along with us. In the Srāddha organised by men for us, your seat shall be the frontal one. We are telling you the truth. By means of garlands, perfumes and by food, they will adore you at the outset.
Vayu Purana, Chapter 66 gives the ten names of Vishvedevas.
विश्वे(श्व)देवास्तु विश्वाया जज़िरे दश विश्रुता:।
क्रतुर्दक्षः श्रवः सत्यः कालः कामो धुनिस्तथा॥ ३१ ॥
कुरुवान्प्रभवांश्चैव रोचमानव ते दश।
धर्मपुत्राः स्मृता ह्येते विश्वायां जज्ञिरे शुभाः॥ ३२॥
The ten well known Visvedevas were born of Višvā. Kratu, Daksa, Šravas, Satya, Kala, Kāma, Dhuni, Kuruvān, Prabhavān and Rocamana were the ten as such. They are all known as the ten son of Dharma. They were the auspicious sons born of Visvá.
Matsya Purana, Chapter 203 also gives the ten names of Vishvedevas with slight variation.
संकल्पायाश्च संकल्पस्तथा पुत्रः प्रकीर्त्तितः।
मुहूर्त्ताश्च मुहूर्तायाः साध्याः साध्यासुताः स्मृताः।। १० ।।
मनो मनुश्च प्राणश्च नरोषा नोच वीर्यवान्।
चित्तहाय्ययनश्चैव हंसो नारायणस्तथा॥ ११॥
विभुश्चापि प्रभुश्चैव साध्या द्वादश कीर्त्तिताः।
विश्वायाश्च तथा पुत्रा विश्वेदेवाः प्रकीर्त्तिताः।। १२।।
क्रतुर्दक्षो वसुः सत्यः कालकामो मुनिस्तथा।
कुरजो मनुजो वीजो रोचमानश्च ते दश॥ १३॥
Sankalpa gave birth to Sankalpa, Muhurtas to Mahurtas, and Sādhyas gave birth to Sādhyas. Mana, Manu, Prāņa, Naroșā, Noca, Vīryavān, Cittahärya, Ayana, Hamsa, Närāyana, Vibhu and Prabhu were the twelve Sadhyas. These were the sons of Sadhyas. Visva gave birth to Wisvedewas. Kratu, Daksa, Vasu, Satya, Kālakāma, Muni, Karaja, Manuja, Vīja, Rocamāna, were the ten Viśvedevas.