This is a good question. Eula May is mentioned seven times in the book. She was the the leading phone operator in Maycomb. This means that she had the task of issuing public messages.
In To Kill a Mockingbird, she appears in three chapters.
First, she announced that there was no school owning to a freak snowstorm. Here is the text:
The telephone rang and Atticus left the breakfast table to answer it. “That was Eula May,” he said when he returned. "I quote—‘As it has not snowed in Maycomb County since 1885, there will be no school today."
Second, she has a conversation with Calpurnia about a mad dog in Maycomb. Calpurnia wanted her to warn others (whoever had a phone) that a mad dog was coming.
Third, she appears for the final time when Aunt Alexandra called her to get a doctor after Aunt Alexandra realized that Jem and Scout were attacked. Soon thereafter, Atticus called her to get Heck Tate. Atticus wanted Heck to know that someone intended to hurt his children.
As for what did Eula May gave Atticus, she gave an announcement that school was closed, and she got the doctor and sheriff for Atticus when he needed it.