Shia Muslims follow the Prophet Muhammad (SAWA) in every matter in religion and it is a confirmed fact among all the Sunni and Shia scholars that the Prophet Muhammad (SAWA) never prayed on a carpet nor put his forehead in prayers but only on earth. He openly said (The earth was made for me as place of prostration ( Sojood) and source of purification (Tayammum). جُعِلَت لي الأرضُ مسجداً وطَهوراً
This Hadeeth was narrated in Bukhari 438 and Muslim 521 and many other Sunni books of Hadeeth.
This confirms that the Shia practice in the real Prophetic practice.