From various records on familysearch, he was b. in Missouri June 28, 1894 or 1895 to Alfred G and Margaret (possibly Statler) Pulliam. On his WWI draft registration in 1917 he lists himself as single. In the 1920 census he is married to June. I didn't find a marriage record, but you might try the records clerk for Kelley, Carter Co., MO and look between those dates. Her death record 1970 is CA doesn't list a maiden name - no image online, so you might want to try to obtain the actual certificate to see if there are more details
U S Census, 1920 Kelly, Carter, MO
Citing this Record: "United States Census, 1920," index and images, FamilySearch (https://familysearch.org/pal:/MM9.1.1/M847-Q9R ), Richard A Pullem in household of Alfred G Pullem, Kelly, Carter, Missouri, United States; citing sheet 1A, family 9, NARA microfilm publication T625, FHL microfilm 1820908.
Alfred G Pullem Head M 74 Missouri
Margret Pullem Wife F 64 Missouri
Richard A Pullem Son M 25 Missouri
June V Pullem Dau-in-law F 24 Missouri
More records on Richard and family:
California, Death Index, 1940-1997
Citing this Record: "California, Death Index, 1940-1997," index, FamilySearch (https://familysearch.org/pal:/MM9.1.1/VGR1-3ND ), June V Pulliam, 05 Dec 1970; citing Department of Public Health Services, Sacramento.
Name: June V Pulliam
Death: 05 Dec 1970 Tulare, California
Birth Date: 05 Jun 1895 Birthplace: Missouri
Missouri, Marriages, 1750-1920 (don't know if this record is related)
Citing this Record: "Missouri, Marriages, 1750-1920," index, FamilySearch (https://familysearch.org/pal:/MM9.1.1/V28N-2VM), Alfered G. Pullam and Margaret Statler, 13 Mar 1870; citing Iron,Missouri; FHL microfilm 915142.
Name: Alfered G. Pullam
Spouse: Margaret Statler
Marriage: 13 Mar 1870 Iron,Missouri