George Gilbert Boyer (b. 1890) was the half brother to my grandmother, Lenore Boyer (b. 1892), and her brother, Clark Irving Boyer (b. 1894). They shared the same father, William Spencer Boyer. I do not know the name of George's mother, but Lenore and Clark's mother was Mary Josephine Dawson.
William Spencer Boyer was the son of Spencer Smith Boyer and Sarah Jennette Mechem. They took care of George Gilbert when he was little. My grandmother remembered going to visit George at her grandmother's home. I have more information on William if you need it.
You really solved a mystery for me, too. I wondered what happened to George. The last record I have of him is the 1917 WWI Draft records. I had no idea he died so early, but I couldn't find him in the 1920 census. Do you have any idea how George died? I did find his son's obituary (Joseph William Boyer), which stated George died when Joe was 9 years old, so that would have been around 1922. Are you related to George?