Dear Theresia,
This could be the record of their marriage:
"Georgia, County Marriages, 1785-1950," database with images, FamilySearch(https://familysearch.org/ark:/61903/1:1:KXVM-9RC : 18 July 2016), William Porterfield and Delta Ivey, 29 Dec 1901; citing Marriage, Jackson, Georgia, United States, county courthouses, Georgia; FHL microfilm 325,654.
Do you believe IVEY to be the surname of your g-grandmother? Or is that her middle name? You may be able to find her in the 1900 census if it is her surname.
Hope this helps! -NGP