Mrs. Roberts was the wife of the Muggle man who managed the campground near to where the Quidditch World Cup was held in 1994. She had two children with him, including at least one son, who was her youngest child. The family lived together in a stone cottage at the front of the campsite.
The Roberts family were attacked by Death Eaters the night after the Quidditch match. One of the Dark Wizards flipped Mrs. Roberts upside down in mid-air, making her nightdress fall down, and revealing her "voluminous" drawers to everyone. The other Death Eaters laughed as she struggled to cover herself. She was not seriously injured during the incident.
Mrs. Roberts' memory was presumably altered to forget the incident.