The IL marriage index lists the marriage of Mamie Isabell Creed to Richard E Condon 20 Nov 1900 in Will Co IL.Do you think that "Mamie" is a mistake in this index. Somethimes these original records are hard to read and the person compiling the index just takes a good guess.There is also a Lucy Creed m Ernest Oram 25 Feb 1892 in Will Co IL. (Possibly a sister??)
The only other Will Co marriage I find in this index is Thomas J Creed m Elizabeth Shay 6 July 1857.
The 1900 Will Co census which would have been before November might show Mary/Mamie still living with her parents.