Sri Jaganath Svami appears as Sri Ram Chandra to Valmiki

Lord Jagannath is the Param Brahma and ever friendly to the devotees. The Lord has shown His appearance to devotees in the forms they conceived in their minds and wanted to see Him in. Lord Jagannath satisfied Valmiki, the author of the great Ramayana epic, by showing him His Raghunath Besha, which is enlisted as one of several Beshas.
Realising the fact that Lord Sri Jagannath is Himself Param Brahma in appearance, Valmiki in his advanced age, proceeded on foot to Puri, the Jagannath Dham alone to see his Lord Sri Rama Chandra, armed with bow and arrows in Lord Sri Jagannath. This pious desire inspired him to travel, covering a long distance.
On his arrival at Puri, he hastened to enter the temple, by ascending the Baisi Pahacha (22 number of steps) and stood in front of the idol of Lord Jagannath on the Ratna Sinhasan (golden throne). From a little distance, he could see the Param Brahma Lord Jagannath with round black eyes, the Sri Vigrahra (sacred idol) without hands and feet and ears, seated and being worshipped. He could not see Param Brahma, according to his conception in the form of Sri Rama Chandra armed with bow and arrows. He was disappointed and left Puri, without even taking any food or drink. He crossed Atharnala
(a road bridge over eighteen nalas) and rapidly proceeded from Puri to Kashi via Batamangala. On the command of Lord Jagannath, Hanuman, who sits on the road bridge over Atharanala, and obstructed Tulsi Das from proceeding to Kashi. Valmiki paid no heed to the indication of Hanuman and proceeded ahead on the road to Kashi.

On the way, in a village called Malatipatapur, Valmiki halted at night in a place called Tulasi Chouwara (elevated platform having sacred Tulasi tree in a pot). Valmiki, out of fatigue and frustration, not seeing Sri Ramachandra in Param Brahma Sri Jagannath, fell asleep. While sleeping in his dream he saw Queen Mother Sri Mahalaxmi, telling Her Lord Jagannath that no devotee returns from Puri without taking Mahaprasad in the form of sacred cooked rice (avada) and curry which She cooks everyday, but devotee Valmiki has left Puri without food and drink. She requested Her Lord Jagannath to proceed Himself in disguise of a small boy taking the sacred rice and curry, which is called Mahaprasad, and offer him to partake. Valmiki, when asked by the boy to take the Mahaprasad, told him that he would not take the sacred rice and curry without seeing Sri Ramachandra in Lord Sri Jagannath, who is hailed as Param Brahma. The boy asked him to open his Ramayana manuscript, which Valmiki had with him, written on palm leaves and bound in red cloth, and asked him to refer to Doha 117 - from the 5th Chowpahi to 8th Chowpahi, which Valmiki himself had written, and to read the Balakanda.

Binu Pada Chalai Sunai Binukana,Kara Binu Karama
Karai Bidhi NanaAnana Rahita Sakala
RasabhogiBinubani Bakata JogiTana Binu Parasa Nayana
Binu DekhaGrahai Ghrana Binu Basa AshesaAsi
Samabhati Alaukika KaranaMahima Jasu Jai Nahin
Barana.

This means:
He is that Param Brahma who walks without feet, hears without ears, does various works without hands, tastes all sorts of items and juices without mouth, touches all without skin, sees all without eyes, and smells all without nose. That Param Brahma is so extraordinarily mysterious, that it is unknown to gods even.

Then the boy said, "Lord Jagannath is the Param Brahma which you have narrated in your above Dohas and poems. He is residing in Sri Mandir and being served by Queen of the universe Mahalaxmi and being bound and tied with the devotional thoughts of his devotees". The boy narrating this told Valmiki to return and look again, and he could see Him in the Form he desired and described in Ramayana.
Valmiki, being emotionally charged and overwhelmed by the words of the boy, resumed his return journey to Puri, came running and reached Puri, ascended the Baishi Pahachas and prostrated before the Lord sitting in Ratna Sinhasan and in the process, Valmiki lost consciousness. Regaining his senses, he looked at Lord Jagannath with folded hands in standing position. He became surprised to see Sri Ramachandra with bow and arrows in hands in the Ratna Sinhasan, in place of Lord Jagannath. He begged excuse and prayed to the Lord to forgive him as he could not recognise Him and could not realize his own version written in Ramayana.

Spontaneoulsy, Valmiki wept profusely and tears rolled down from his eyes and he confirmed his version by the inspiration of the Lord in the immortal poem, which came out from his mouth.

Johi Rama Sohi Jagaddisha,
Dina Hine Ananta Parbata Shesha

This means:
Lord Jagannath is Rama, and Rama is Lord Jagannath. He is the protector of the poor, down-trodden and neglected, like the mountain is being protected by Sheshanaga, (Ananta) upholding the same by placing the earth over it.

Valmiki became satisfied and his journey to see Lord Ramachandra in Puri in Param Brahma Jagannath was fulfilled completely. He returned from Puri Dham on foot, meditating over the event.

Jai Ram...Sri Ram... Jai Jaganatha