The calendar of Persian festivals
Jašn
From the Book of the Crown (Kitāb al-Tāj)

We find an account about the offering of presents on the days of the festivals of Mihragān and Nōgrōz in the Book of the Crown, written by a Persian scribe of the 8th century (but falsely attributed to Jāḥiẓ). It is based on a Pārsīg text of the Sasanian times. In it we read that: The feast of Nōgrōz marks the summer solstice, and the feast of Mihragān the winter solstice.
Picture
From the Kitāb al-maḥāsin waʾl-aḍdād

The book Al-maḥāsin waʾl-aḍdād, attributed to Jāḥiẓ, but probably compiled in the late eleventh century, contains a chapter on two Persian festivals, Nōgrōz and Mihragān. The compiler has quoted an account of the origins and celebration of Nōgrōz in Persian times by Xusravī (Arab. Kisrawî), but has omitted his description relative to the Mihragān festival. He also deals with presents by different people on the occasion of Nōgrōz. An important thing in this description, for the survey of the Persian calendars, is the division of a month into six equal parts.

The virtues of the Nōgrōz and the Mihragān
The reason of water-sprinkling
The virtues of the presents (on the occasion of the feasts of Nōrōz and Mihragān)
The calendar of Persian festivals
According to Bērōnī’s Canon Masudicus

Bērōnī treats of the calendar of Persian festivals in his two books: One, a longer account, in the Vestiges of the Past (الاثار الباقية عن القرون الخالية), chapter IX, “on the festivals in the months of the Persians”; the other, a short account, in the Canon Masudicus (القانون المسعودي), an encyclopaedia of astronomical sciences, second part, chapter 11, “on the festivals of the Persians and their days during the Aryan period”.
PhotoA Persian Lady (Bēšābūr, third century)
The month of Spendārmed, the day of Spendārmed

On the day of the festival of the women, called Mizdgīrān
PhotoA Parsi Lady (India)

On the 5th day (or Spendārmed rōz) of the Persian month Spendārmed, there was the feast of Spendārmed (Av. Spәṇtā Ārmaiti), a holy Immortal (or, a goddess) that represents the earth. On this day the Yasna ceremony was performed, and the draona of Seven Amәṣa Spәṇta consecrated.

It was a day on which the wives made requests of their husbands and claimed the satisfaction of their wishes and extravagant demands, and the men used to make the women liberal presents. It was known among the Persians (and Parthians) as the Jašn ī Mizdgīrān (/ Jašn cē Miždgīrān), i.e., the ‘present-taking feast’.  Bērōnī described it as the annual women’s day festival (عيدالنساء), and stated that this custom was still flourishing in his time at Spāhān, Ray, and in the other districts of Pahlav.

This day was also famous for the charm written on paper pieces, or on the skin of a deer, with saffron water, to ward off the stings of scorpions. According to Bērōnī the Persians fixed three such paper pieces on three walls of the house; and according to a Persian “Rivāyat” the charm was posted on the front door of the house. They also fumigated the house with five things: storax, the horn of a small cattle, frankincense, wild rue, and cotton-seeds. Before inscribing the charm or fumigating the house the Vāz of Aṣa Vahišta was performed. On this day, the special formula of gravel (Nīrang ī Sangrēzag) was consecrated, and gravel or sand was sprinkled in all the corners of the household to repel noxious insects and reptiles.

An account of some Persian festivals and some miscellaneous matters

در چگونگی ِ پديد آوردن ِ ماهها و سالهاء کيان و نهادن ِ آيينها و توقيعات مشهوره

There exists a small treatise in Persian about the calendar and calendar customs of the ancient Persians. Its author, a Pārsī priest (dastōr), has drawn his account from some secondary Persian sources, especially the Nōrōznāma (attributed to Khayyām).