In the forest, Sita met Anasuya, wife of the rishi Atri.
"Listen to my story," Anasuya said. "Three handsome men once came here, saying 'We have fasted twelve years. Feed us from your breast.' I realized they were the gods Vishnu, Brahma, and Shiva. I used my yogic powers to turn them into babies and let them suckle. Lakshmi, Saraswati, and Parvati then came and asked me to release them. I made them gods again, and they departed."
Then Anasuya gave Sita gifts: a garment that stayed ever-clean, a garland that stayed ever-fresh, and cream to make her skin ever-soft.
Inspired by: Sita: An Illustrated Retelling of the Ramayana by Devdutt Pattanaik
Notes: This story is on p. 106 of the book. In Valmiki's Ramayana, the meeting with Anasuya beings in the Ayodhya Kanda (Book 2), sarga 118. In Valmiki's version, Anasuya also gives Sita jewels.
The idea that the three men who came to Anasuya in the forest were gods comes from Indian folklore; in other versions of the story, they are mortals. The blessing they give to Anasuya is that she became the mother of Dattatreya, who is worshiped as Adinath, a form of Vishnu, Brahma, and Shiva; you can read more at Wikipedia.