JWR says SR had high-quality education.
John W. Rigdon lecture, MS 0354, Special Collections and Archives. University of Utah, J. Willard Marriott
Sidney Rigdon, after his brother Loamma Rigdon had gone to Lexington K. Y., he borrowed all the histories he could get and began to read them. His parents would not let him have a candle to read by night. He therefore gathered hickory bark; there was plenty of it around the old farm, and he used to get it and at night throw it in the old fire place and then lay with his face bent towards the fire and read history till nearly morning unless his parents got up and drove him to bed before that time. In this way he became a great historian, the best I ever saw. He seemed to have the history of the world on his tongue's end and he got to be a great biblical scholar as well. He was as familiar with the Bible as a child was with his spelling book. He was never known to play with the boys; reading books was the greatest pleasure he could get. He studied English Grammar alone and became a very fine grammarian.