Answer by taking a quote from the following article:

"Ode to Billie Joe" is a 1967 song written and recorded by Bobbie Gentry, a singer-songwriter from Chickasaw County, Mississippi. The single, released in late July, was a number-one hit in the United States, and became a big international seller. Billboard ranked the record as the No. 3 song for 1967 (the other two were #2 "The Letter" by the Box Tops and #1 "To Sir With Love" by Lulu). The song is ranked #412 on Rolling Stone's list of "the 500 Greatest Songs of All Time" and at #144 in Pitchfork's 200 Best Songs of the 1960s.

Questions arose among listeners: what did Billie Joe and his girlfriend throw off the Tallahatchie Bridge, and why did Billie Joe commit suicide? Speculation ran rampant after the song hit the airwaves. Gentry said in a November 1967 interview that it was the question most asked of her by everyone she met. She named flowers, an engagement ring, a draft card, a bottle of LSD pills, and an aborted baby as the most often guessed items. Although she knew definitely what the item was, she would not reveal it, saying only "Suppose it was a wedding ring."  "It's in there for two reasons," she said. "First, it locks up a definite relationship between Billie Joe and the girl telling the story, the girl at the table. Second, the fact that Billie Joe was seen throwing something off the bridge - no matter what it was - provides a possible motivation as to why he jumped off the bridge the next day."  When Herman Raucher met Gentry in preparation for writing a novel and screenplay based on the song, she said that she had no idea why Billie Joe killed himself. Gentry has, however, commented elsewhere on the song, saying that its real theme was indifference:  Those questions are of secondary importance in my mind. The story of Billie Joe has two more interesting underlying themes. First, the illustration of a group of people's reactions to the life and death of Billie Joe, and its subsequent effect on their lives, is made. Second, the obvious gap between the girl and her mother is shown when both women experience a common loss (first Billie Joe, and later, Papa), and yet Mama and the girl are unable to recognize their mutual loss or share their grief.  The bridge mentioned in this song collapsed in June 1972. It crossed the Tallahatchie River at Money, about ten miles (16 km) north of Greenwood, Mississippi, and has since been replaced. The November 10, 1967, issue of Life Magazine contained a photo of Gentry crossing the original bridge.

were the questions ever answered?
Although she knew definitely what the item was, she would not reveal it, saying only "Suppose it was a wedding ring.