Edith Barton

Edith Barton (b. 1957) (d. 1997) was the mother of Laura Barton, Barney Barton, and Clint Barton, which in turn makes her the mother-in-law (so to speak) of Natasha Romanoff and the grandmother of Cooper Barton and Lila Barton.
Edith was a complicated woman. An omega, she was disowned by her parents for not meeting their expectations and had all three of her children with an unnamed father. At some point, most likely due to her problems with drugs and her subsequent imprisonment because of it, she was forced to give up custody of her children to the state. Because of this, her children were stuck in foster care, potentially during the time that Laura was undergoing cancer treatment. Her younger son Clint did wind up running away from foster care, however he also killed his brother Barney due to unknown reasons.
In 1997, shortly after getting released from prison, Edith died from a drug overdose.