Grace was born November 14, 1939 in Ortley, South Dakota to Nicholas and Julia (DeMaris) Pies. Grace grew up on a farm near Ortley and attended country school. On May 12, 1964, she married Virgil Onnen in Gillette, Wyoming. After their marriage, Grace lived and worked various jobs in Iowa, Nebraska and South Dakota, all while raising 10 children. In 1990, they moved to Florida and Grace continued her education and graduated from Locklin Technical College in Carpentry. She loved woodworking and made all sorts of items from clocks to benches to jewelry boxes. Grace was very artistic and loved drawing, painting and doing scroll saw artwork. Virgil passed away on February 11, 2001 and Grace later moved to Osmond, Nebraska in 2002. She lived there until 2010 when she moved to Yankton. Besides woodworking and art, Grace also loved reading, fishing and family gatherings. She was a hard worker and devoted her life to her husband and children.

Grace is survived by 10 children: Cheryl (Dan) Kiichler of Norfolk, NE, Marty Onnen of Wayne, NE, Jeanise (Bruce) Moore of Douglas, GA, Sandy McLean of Rozet, WY, Vicki (Trevor) Critchley of Wausa, NE, Val (Matt) Helmer of Yankton, Dave Onnen of Pilger, NE, Lisa (Randy) McKittrick of Milbank, SD, Stephanie (Troy) Thennis of Kings Mountain, NC and Stacey Giehll of Yankton; 30 grandchildren; 44 great grandchildren; one sister; four brothers; and many, many nieces and nephews.

Grace was preceded in death by her parents, husband, Virgil Onnen; two grandchildren: Michael and Amanda Geyer; two sisters and three brothers.