I was at the courthouse in Shell Lake the other day and was able to find some information on the Thompson family of Minong. I'm not sure what information you may already have, so some of this may be redundant for you.
The Thompson family is, indeed, buried in the Minong Greenwood Cemetery, including these names:
Cecelia "Tina" Mary - b. 15 Aug 1921 - d. 8 Mar 1982 - wife of Hiram, maiden name Johnson -- Death Record Vol. 22, pg 2
George Monroe - b. 2 Dec 1923 - d. 27 Feb 1983 - Wife's name was Elizabeth Chartier -- Death Record Vol. 22, pg 175
Hiram O. - b. 4 May 1916 - d. 26 Feb 1988 (no death record found in Washburn Co.)
Keith Allen - b. 17 Oct 1971 - d. 7 Dec 1991 - son of Norman "Smokey" Kenneth & Linda Marie (Tolene) Thompson -- Death Record Vol. 24, pg 537
Marian Elizabeth - b. 9 Apr 1921 - d. 23 Mar 1996 - wife of Melvin, daughter of George & Helen Marie (Burgraff) Kestel -- Death Record Vol. 26, pg 148
Melvin - b. 23 Mar 1929 - d. 18 Jul 1998 - married to Marian Elizabeth Kestel -- Death Record Vol. 27, pg 107
Norman "Smokey" Kenneth - b. 7 Jul 1927 - d. 20 Aug 1994 - Wife's name Linda Marie Tolene -- Death Record Vol. 25, pg 417
Thomas Miron - b. 17 Sep 1914 - d. 28 Nov 1987 (your father?) (no death record found on file in Washburn Co.)
Also a stone is in place at the same cemetery for Elizabeth, wife of George Monroe Thompson. There is no death date, so she may still be living.
Here is your Grandfather and Grandmother's death record information:
Death Record Vol. 15, pg 239 -
THOMPSON, Thom K., male, white, married, farmer, residing in Minong. Son of Knute and Julia (Burns) Thompson. Born 23 Dec 1877 in Norway, died 8 Oct 1958 at the Spooner Hospital, cause of death being Cerebral Areriosclerosis due to Coronary Sclerosis/auricular fibrillation/cardiac decompensation. He was 80 years of age. Informant for the death record was Hiram Thompson, son of deceased. His doctor was Frederick Goetsch, M.D., Spooner. Funeral home director in charge of the arrangements was Robert Wilkinson with burial on 10 Oct 1958 in the Greenwood Cemetery, Minong.
Death Record Vol. 17, pg 412:
THOMPSON, Mary, female, white, widowed (wife of Thom K.), housewife, residing at Minong. She was born 27 Dec 1890 at Eleva, Trempealeau Co., WI to Ole and Alice (Ness) Hendrickson. She died on 19 July 1967 at the Spooner Hospital from Mesenteric vascular occlusion/severe generalized artersclerosis. She was 76 years of age. Informant for her death record was Mrs. Alice Hobbs, daughter of deceased. Frederick Goetsch, M.D., Spooner. Dahl Funeral Home, Spooner, in charge of the arrangements. Burial in Greenwood Cemetery, Minong.
I hope this information will give you more leads and help you break through your brick wall. Good luck with your research.