My grandmother's brother was married in the 1940s to a woman with whom he had three children. They divorced and the mother moved fifteen miles away and never really interacted with the family again. Mom told me that one of these children (her first cousin) died and the obituary was in an online paper in the town where the cousin lived.
Now, several years later, I am getting around to working on it a little more. Problem is that I didn't keep any of the information mother gave me.
So I searched at GenealogyBank, using the name of the uncle in the keyword box:
The article came up in my results. If the name had been more common, I could have searched by state, or put in another keyword. I didn't know the name of the person who died, but I did know the name of the uncle and remembered that he was listed as the biological father in the obituary.
Use those keyword searches and take notes when your mother gives you genealogical information.