We know Tammy best for her solo hits and legendary duets with George Jones, but the corners of her catalog reveal intriguing pop crossovers and surprise collaborations. She completed a country dream team by joining Dolly Parton and Loretta Lynn for heaven-sent harmonies on "Silver Threads and Golden Needles," and she crossed all kinds of borders by tackling the passion-packed pop ballad "A Woman's Needs" alongside Elton John.