Mystery Monday - Who was Mary Bradley's mother?

Mary Bradley is my second great grandmother on my mother's paternal side (William Lawbaugh ->Effie Bender->Mary Bradley).

Mary Eugenia Bradley was born 18 December 1867 in LaSalle county, Illinois.  Her parents are listed on her death certificate as Charles Bradley and Kate Bradley.  The informant listed on the death certificate was her daughter, Matilda 'Tilly' (Bender) Case.

Both my mother and one of her cousins remember their 'Grandma Bender' (Effie May Bender), Mary's older daughter & Tilly's older sister, telling the story about how her mother, Mary Bradley, was born illegitimately to a Jewish woman and forced onto her father's new bride to raise.  They both also remember a story that Grandma Bender remembers a visit to Mary by the supposed biological mother.

Here are some of the ideas I have researched in my attempt to find an answer to this family story:

Birth Records

• Birth Records were not kept in the state of Illinois until 1916.
• LaSalle County, Illinois starting keeping birth records in 1877 but have no earlier records.

Census
An analysis of the census records is not clear either:

• 1870 Federal Census - living with John and Kate
• 1880 Federal Census - living with John and Kate and 3 brothers
• about 1883 - John Bradley dies
• 1885 Kansas Census - living with Kate and 3 brothers
• 1900 Federal Census - living with husband, William Bender.  Kate is living in Chicago with her 3 sons.  She indicates that she has had 5 children and only 3 are living.
• 1910 Federal Census - Mary is living in Kansas with her second husband.  Kate is living with her oldest son and his family in Chicago.  She indicates that she has had 3 children and 3 are living.

It is very interesting that after moving to Chicago, Kate (Cary) Bradley has indicated only 3 children are living when Mary is clearly alive in Kansas.

Marriage Records

• Mary Bradley's marriage certificate to William Bender dated 17 December 1877 does not mention Mary's parents.  There is a certificate signed by John Bender (William's father) attesting to both Mary and William being of age (18 and 19 respectively).
• The marriage certificate for John Bradley and Catherine Cary is definitely more interesting.  They applied for a marriage license in LaSalle County, Illinois on November 18, 1867.  The copy of the license I received states that license # 1243 was 'not returned, missing'. 
• I have also received a copy of the St. Columba Church marriage records (Ottawa, LaSalle, Illinois) for Charles and Kate.  The church records indicate that Charles and Catherine were married November 18, 1867.  The marriage was witnessed by William Edding and Mary Noonan.

The marriage date for Charles and Catherine is only 31 days before Mary was born.  I find it very unlikely that a woman in 1867 would wait until she is 8 months pregnant before marrying the father of her child.  Considering the year, I would expect a woman to have gotten married as soon as possible to hide the fact she was pregnant before marriage.

Conclusions
I have not reached any conclusions about who Mary Bradley's mother is. 

I do find the evidence in favor of Kate Bradley being Mary's mother on the thin side.  The only person who has stated that fact was Mary's daughter.  She was obviously did not have first hand knowledge of the birth since she was not there. 

There is also no proof yet that another woman is Mary Bradley's mother.

The only clue I have to the mystery Jewish woman is that her last name might have been Udell.  This name was given to my mother's cousin by Grandma Bender in a conversation.

I am following up on another research idea right now.  I have sent an inquiry to the Catholic Church, St. Columba, in Ottawa, Illinois to see if they have any birth or baptismal records for Mary Bradley.  This is the church that Charles and Kate got married at just a month before Mary's birth.

I will keep you updated when I receive a response.