In our mythology there have been a few Rishi who had Divine cows. These Divine cows were from Kaamdhenu family. Here are the names of those Rishi and the incidents related to it. The first three names are of Rishi who had the divine cows, and who entertained a King and his army with that cow. Kings got very jealous with those Rishi and had a kind of war with Rishi. The last two Rishi did not have any cow but had extraordinary powers and Mani (gem). They all could have what they wanted, they all hosted the Kings and three kings out of the four were jealous with Rishi's possession. Perhaps Bharat was not jealous with Bharadwaaj's possession because he was not an ordinary human being, he was the incarnation of Vishnu's Sudarshan Chakra.
(1) Maharshi Vashishth -
Vashishth Jee was the Purohit of Soorya Vansh - Raam's family. He had the Kapilaa cow to serve him for his Yagya and other Rishi's needs. Once King Vishwaamitra came that side while he was on hunting trip. he came to Vashishth Jee's Aashram. Vashishth Jee requested him to accept his hospitality. Vishwaamitra Jee was hesitant to accept it as they were many people and he thought that Rishi is only Rishi, how can he entertain them. But he agreed as Rishi insisted. Vashishth Jee entertained him and his army with the help of that cow. Vishwaamitra Jee was very impressed with that cow and asked him for her. Vashishth Jee could not give her to him as she fulfilled all his needs. Vishwaamitra Jee's plea was that since he was a king, the cow's utility was more for him than for the Rishi. When Vashishth Jee did not give her to him, he used his force to take her, but the cow produced various kinds of army which pushed Vishwaamitra Jee's army away.
Not only Vishwaamitra Jee, but even the eighth Vasu named Dyau stole his cow. Once all the Vasu went to see Vashishth Jee. Dyau's wife saw the cow and got attracted to her. She asked her husband what were the qualities of that cow. He replied that whoever drank her milk would never become old. Now she had a friend for whom she wanted that cow so that she would remain always young. She expressed her wish to her husband to have that cow. Although Dyau knew that it was wrong to steal Rishi's cow but still he stole the cow for his wife. As Vashishth Jee came to know that Vasu had stolen the cow, he cursed all the Vasu to be born on Prithvi as human beings. Later he came to know that Dyau had stolen his cow so he cursed him that "Go, and be born as a human being on Prithvi and since you were so fond for your wife, be without wife for your whole life." Dyau brought back the cow and asked for Rishi's forgiveness. Rishi said - "Though you will be born as a human being you will earn name and fame as a good man."
Now who would bear them? Thinking thus they were going that they met Gangaa who was also cursed to be born on Prithvi as a human being, so they requested her to be their mother and give them Mukti as soon as they were born. Gangaa said - "But at least one has to live there." Then Dyau agreed to live there and each of the remaining 7 Vasu gave him 1/8th of their power to him live on Prithvi. Thus Shaantanu had 8 sons from Gangaa, out of them 7 were given Mukti as soon as they were born and the 8th one remained alive. He was later known as Bheeshm. He remained without wife his whole life.
(2) Maharshi Jamadagni Jee -
Maharshi Jamadagni Jee was the father of Parashuraam Jee. he also had Kaamdhenu cow for his Aashram needs. Once he entertained king Sahastrabaahu (Arjun) and his army. Seeing the qualities of the cow, Sahastrabaahu also wanted to take that cow, so he asked the Rishi to give that cow to him, but Jamadagni Jee also refuse to give the cow to him. At this he wanted to take her to his capital Maahishmatee Puree forcefully, but could not take her as she also produced lots of army which pushed Sahastrabaahu's army back. Later his sons came, killed Jamadagni Jee and took the cow to their capital. Later when Parashuraam Jee came to the Aashram, he went to Sahastrabaahu, killed him and brought the cow back to his father's Aashram.
(3) Muni Bharadwaaj -
It is worthwhile here to mention Bharadwaaj Muni's name also who hosted Bharat and his army while they were going to bring Raam back to Ayodhyaa. Although it was not not through cow, but through his Yog power. All, including Bharat, were astonished to see his hospitality for such a large group of people. Vaalmeeki Jee has described it very beautifully [V-Raamaayan, 2/35/91]
(4) Rishi Gaurmukh -
His story comes in Matsya Puraan and in Varaah Puraan. Although he did not have any cow, but he had a Mani given by Vishnu with which he could fulfill any desire. It was Chintaamani. He entertained Durjaya named king through this Mani. As Vishwaamitra and Sahastrabaahu wanted those cows for themselves, he also wanted that Mani for himself. In the end Vishnu killed him with His Chakra.