Both the Gaines and McCulloch families arrived in Washington from the Midwest at the turn of the twentieth century. Edward F. Gaines (1886-1944) was born in Missouri and moved as a teenager with his family to a farm near Chewelah. The McCulloch family and young Xerpha Mae (1891-1970) left Wisconsin to homestead near Othello.

Edward F. Gaines graduated from the State Normal School at Cheney (now Eastern Washington University) in 1907. He then worked as a public school principal and teacher in Ritzville, where he met Xerpha Mae McCulloch, who graduated from high school there in 1910. Edward left Ritzville in 1909 to continue his education at the State College of Washington (now Washington State University) in Pullman where he earned his bachelor and master of science degrees in agronomy in 1911 and 1913, respectively.

Throughout his career, Edward was associated with several plant genetics pioneers, as a student, colleague, and mentor. One of his students was Karl Sax, who received his bachelor's degree in agriculture from WSC in 1916 and became a leading cytologist and plant geneticist, and National Academy of Science member. Sax credited Edward Gaines for introducing him as an undergraduate to research in plant breeding, and encouraging his pursuit of graduate studies, and they remained correspondents throughout Gaines's lifetime.

Another lifelong correspondent was Harry B. Humphrey, who had been Edward's botany professor at WSC and became long-time phytopathologist with the Bureau of Plant Industry of the United States Department of Agriculture (USDA). In an obituary for Edward in the journal Phytopathology, Humphrey wrote that his most important contributions centered on his genetic studies of bunt resistance in wheat and smut resistance in wheat and oats. Gaines developed the Triplet, Ridit, and Albit wheat varieties to increase both yields and smut resistance. Orville Vogel, renowned wheat breeder at WSU with the USDA, named two wheat varieties for Edward Gaines: Gaines (1961), the first semidwarf winter wheat for commercial production, and NuGaines (1965).

Xerpha McCulloch Gaines established her own legacy at WSC. Though she pursued her education at WSC in the first years of marriage, raising her four children delayed her graduation until 1930 when she received her bachelor of arts degree in education and was a member of Phi Beta Kappa.

Married in 1912, Edward F. and Xerpha McCulloch Gaines made their home in Pullman as Edward continued in his position as Assistant Cerealist and Instructor of Agronomy. Edward spent a semester at Harvard University in 1915 studying genetics and plant breeding under Dr. Edward M. East at the Bussey Institution for Research in Applied Biology. He returned in 1920, and received his Doctor of Science degree in 1921. At the same time, he continued on the faculty at WSC, rising to Cerealist in 1917 and serving as Assistant Professor of Farm Crops from 1918 to 1926, Associate Professor from 1926 to 1930, and as Professor of Genetics in Agronomy from 1930 until his death in 1944.

Xerpha began a collaboration in 1950 with Dr. Theodore Scheffer of the U.S. Biological Survey to collect plant specimens in the area around Grand Coulee Dam with their results published in a 1957 article: "A Botanical Survey of the Grand Coulee-Eastern Washington," Research Studies of the State College of Washington 25.3 (Sept. 1957): 207-235. In 1957 she accepted an invitation from the Museum of Northern Arizona for a May botanical collection raft trip down the Colorado River through the area soon to be inundated behind the Glen Canyon Dam. She published her results in an article, "Plants in Glen Canyon," Plateau 30, no. 2 (October 1957): 31-34.

For each of the above botanical surveys, Xerpha collected specimens for herbaria. The University of Washington's Burke Museum herbarium today lists nearly 400 specimens collected by Xerpha Gaines, many from the Grand Coulee surveys. A University of Utah publication about the 1957 Colorado River trip noted that Xerpha Gaines collected specimens from 150 species for the Museum of Northern Arizona herbarium. Because of her association with what is now WSU's Ownbey Herbarium, Xerpha duplicated her Glen Canyon specimens there as well as adding her many specimens collected over her years in the Palouse.

After retirement, Xerpha continued her work, identifying specimens from home at her kitchen table. The WSU Agronomy Club and Agronomy and Soils Department dedicated its Spring 1971 Agronomy and Men issue to Xerpha Gaines, noting that "[h]er reputation as an excellent 'seed hawk' was known throughout the Inland Empire and the State." Xerpha listed under "Hobbies, recreational activities, specialties" on a 1957 WSC personnel information form: "Taxonomy of plants and plant collecting Seeds." That lifelong interest culminated in the posthumous publication of a book, co-authored with D.G. Swan, Weeds of Eastern Washington and Adjacent Areas (1972).

In 2008, Dr. Stephen Jones, Director at the WSU Research and Extension Center in Mt. Vernon, released "Xerpha," a new variety of soft-white common winter wheat named after Xerpha Gaines.

Edward and Xerpha Gaines had four children: Edward M. (1913-2000), Xerpha Mae (1915-2003), John (1917-1955), and Grant (1922-1965). Xerpha Mae Gaines was always known as "Mae." All four siblings graduated from WSC. In 1938 Mae married Ramon Kent, who had a long career with the Soil Conservation Service primarily out of the Spokane office. Janice Gaines Walker, daughter of Grant, and Jocelyn Liu, granddaughter of Mae Gaines Kent, were instrumental in the donation of this collection to WSU.