In the 1960s, English rock musicians like the Rolling Stones, Eric Clapton, Led Zeppelin and many others were discovered by American listeners – largely because of the Beatles – and became a smash hit with American teenagers.
Many of these UK groups had been listening closely to African American roots blues and electric blues – black genres that ironically most white Americans didn’t have direct experience of – and were emulating the styles and methods of these African American artists quite consciously. They also often created songs that incorporated motifs and music from the work of these black artists, following the practice common in blues and jazz of appropriating freely from the stew-pot of 20th century African American creativity (much of the material was anonymous in origin, unpublished, out of copyright, etc).
American audiences often assumed that the styles and methods of the British artists were original with these musicians, not recognizing the native roots of the music they were now able to appreciate in its new, white format.
Because of the political situation in America – the Civil Rights movement was just now having an effect and many white Americans still lived in isolation from any of their black fellow citizens, and in some cases looked down on them – the white English artists were able to achieve fame and fortune while their black influencers and sources remained obscure and in comparative poverty.
In a few cases, the British artists were actually sued for plagiarism. Although they were arguably just trying to imitate the practices of their heroes, the fact that they were white gave them commercial advantages. So even if the plagiarism was debatable, it would have been a good gesture on their part to acknowledge the influence, and perhaps even give writing credit and royalties in some cases. The Rolling Stones are generally thought to have been better in this regard, while Led Zeppelin have often been taken to task for failing to give credit (and royalties) where credit was due.
For instance, as Wikipedia notes, “In December 1972, Arc Music, owner of the publishing rights to Howlin’ Wolf’s songs, sued Led Zeppelin for copyright infringement on ‘The Lemon Song.’ The parties settled out of court. Though the amount was not disclosed, Wolf received a check for $45,123 from Arc Music immediately following the suit, and subsequent releases included a co-songwriter credit for him.”