Sayyiduna Abu Sa'id al-Khudri (may Allah be pleased with him) says: "We used to give sadaqat al-fitr as a sa' of dates, or of barley, or of wheat, or of cheese (aqit), or a sa' of raisins."
This is the wording of Yahya bin Yahya's narration. In the narration of Imam al-Shafi'i (may Allah have mercy on him) it is: "a sa' of food, a sa' of barley"; he did not mention the word "or" at this place, and mentioned it after that. Sufyan al-Thawri (may Allah have mercy on him), narrating from Zayd bin Aslam, added these words: "We used to give sadaqat al-fitr in the time of the Prophet (peace and blessings be upon him)," and then he mentioned the rest of the hadith.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الزكاة / 7698