The mural in Rashford's hometown, Manchester, was defaced with the graffiti following England's defeat to Italy in the Euro 2020 final. Black players on the England team have also been subjected to a storm of racist online abuse.
Wellard is is an artist with Withington Walls, a street art community project that created the mural. Rashford's public profile has soared in recent months, in part due to his widely-publicized campaign for poor children to be given more support.
An unidentified man at the mural told the BBC that he went to school with Rashford's brother.
"I come from an ethnic background myself and I understand what it's like to kind of suffer from racism, that kind of stuff," he said, adding "I knew what was coming."