This group of Romney-Rambouillet crosses were interbred and selected for both wool quality and high carcass yield. They became known as Romeldales. Much of the establishment of the Romeldale breed was accomplished by the J. K. Sexton family during the 1940s and 1950s. The Sextons selected the sheep for high rates of twinning, maternal ability, and nonseasonal reproduction. Soft handling wool was also a priority, as was fleece weight and a grade of 60s to 64s.

Romeldale sheep are white, but during the 1960s, colored lambs appeared in the breed. Glen Eidman, a partner of the Sextons, became interested in these sheep and line bred them for several generations, further selecting for fleece quality. He referred to this group of sheep as California Variegated Mutants, usually shortened to CVM. The classic color pattern of the CVM is the badgerface, a light body with a dark belly and dark head. This pattern creates a range of shades of color on a single fleece. Selection has increased the range of variablility in fleece colors to include gray, black, brown, and moorit. Fleece colors darken, rather than fade during maturation.