Answer by taking a quote from the following article:

Born in Cleveland's Fairfax neighborhood, near East 85th Street and Quincy Avenue, to Naomi Womack and Friendly Womack, Bobby was the third of five brothers. Friendly Jr. and Curtis were the older brothers, Harry and Cecil were his younger brothers. They all grew up in the Cleveland slums, so poor that the family would fish pig snouts out of the local supermarket's trash. He had to share a bed with his brothers.

By the mid-1950s, 10-year-old Bobby was touring with his brothers on the midwest gospel circuit as The Womack Brothers, along with Naomi on organ and Friendly Sr. on guitar. In 1954, under the moniker Curtis Womack and the Womack Brothers, the group issued the Pennant single, "Buffalo Bill". More records followed.  Sam Cooke, the lead singer of The Soul Stirrers, first saw the group performing in the mid-1950s. He became their mentor and helped them go on tour. They went on national tours with The Staple Singers. Even though Curtis often sang lead, Bobby was allowed to sing alongside him showcasing his gruff baritone vocals in contrast to his older brother's smoother tenor. During performances, Bobby would sometimes imitate the role of a preacher, which later became his nickname. At just 16, Bobby dropped out of high school.  At the beginning of the 1960s, Cooke formed SAR Records and signed the quintet to the label in 1961, where they released a handful of gospel singles. Then, Cooke changed their name to the Valentinos, relocated them to Los Angeles and convinced them to transition from gospel music to secular soul-and pop-influenced sound. Cooke produced and arranged the group's first hit single, "Lookin' for a Love", which was a pop version of the gospel song, "Couldn't Hear Nobody Pray", they had recorded earlier. The song became an R&B hit and helped land the group an opening spot for James Brown's tour. The group's next hit came in 1964 with the country-tinged "It's All Over Now", co-composed by Bobby. Their version was rising on the charts when The Rolling Stones covered it.  Womack was also a member of Cooke's band, touring and recording with him from 1961. The Valentinos' career was left shaky after Sam Cooke was shot and killed in a Los Angeles motel. Devastated by the news, the brothers disbanded and SAR Records folded. Womack continued to work as a session musician. Between 1965 and 1968, he toured and recorded with Ray Charles.

What was the name of their group?
The Womack Brothers,