Given the following passage  "Since the mid-2000s, the mainstreaming of bands like Wilco and Feist have pushed indie rock into the adult contemporary conversation. In the early 2010s, indie musicians like Imagine Dragons, Mumford & Sons, Of Monsters & Men, The Lumineers and Ed Sheeran also had indie songs that crossed over to the adult contemporary charts.",  answer the following question. Note that the answer is present within the text.  Question: What crossed over?
indie songs