Mary Lou Doll was a mother to hundreds of children.

She welcomed them into her south Minneapolis home, often with little notice. Some came in wheelchairs or with mental disabilities. Many stayed for weeks, others for months at a time.

Doll, an advocate for the disabled who for decades offered her home to provide respite and temporary foster care in Hennepin County, died Feb. 24 at age 90.

Her friends and family remember her as a woman with a big heart who put her beliefs into action, devoting her life to caring for those who needed it most.

"All those years, giving back to the community and making the community better, really just made her a hero in my eyes," said Sue Abderholden, director of Minnesota's chapter of the National Alliance on Mental Illness, who knew Doll as a friend and fellow crusader for mental health policy changes.

"She was just a sweetheart."

Doll was born Mary Lou Flagstad in 1927, the youngest of four children. Her father was a dentist and president of the Sunday school at Riverside Presbyterian Church on Franklin Avenue. Doll developed a passion for the church early in life, where she sang in the choir and played hymns on piano.

She studied social work and education at Macalester College, and she later spent several years teaching second grade in the Minneapolis Public Schools.

A tall, wiry redhead, she met a farm boy named Orval Doll in 1956 at a church group for similarly statured people called "Tip Toppers," according to one of her sons, David Doll.

Two years later, she gave birth to the couple's only biological child, a daughter named Margaret. Margaret was born with phenylketonuria, or PKU, a rare disorder whose symptoms can include delayed development, hyperactivity and seizures. Doll's brother-in-law, Robert Guthrie, later developed the first early screening test for PKU, known as the "Guthrie Test."

Margaret's illness emboldened Doll's mission to help others. She adopted three sons, and from 1981 to 2005 the family hosted more than 300 children in their home, specializing in difficult cases of young people with mental or physical disabilities, said David Doll.

"She really lived out her faith," said David. "She's just going to roll up her sleeves and do the good work."

Doll was an early member of the organization now known as the Arc Minnesota, which advocates for people with intellectual and developmental disabilities.

She tirelessly wrote letters to politicians pushing for better policies and more funding for mental health, and she hosted events for legislators and community members well into her 80s.

In the waning years of her life, she continued to sing in an a cappella group. She remained active in her church and played hymns weekly on a piano at the senior community in which she lived.

She suffered a seizure in December 2017, and her health declined in the following months. She died as the result of a confluence of illnesses.

Doll was preceded in death by her husband. She is survived by three sons, David, Peter and Michael; her daughter, Margaret, and a sister, Virginia Hoyt. A memorial service will be held at 2 p.m. Saturday at Christ Church Lutheran, 3244 34th Av. S., Minneapolis.