As a fulltime Laura Ingalls Wilder researcher (and knitter), I can tell you that she did use double pointed needles. Laura's daughter Rose published THE WOMAN'S DAY BOOK OF AMERICAN NEEDLEWORK and it contains needlework by Rose, Laura, and Caroline. Some of the needlework is on display at the LIW Museum in Mansfield, Missouri, as well as knitting pins, thread, needles and other items used by Laura and Rose. I remember seeing metal knitting needles; don't remember wooden. I've seen at least one knitting pattern book of the family's on display at the LIW Memorial Society in De Smet.
Laura did have arthritis later in life, and in letters she lamented the fact that she had to give up handwork.