Songs for graduation?

my sister had made some videos for family members and now i am making her one. for my grandparents she used Thank You by Keith Urban and for my mom she used The Best Day by Taylor Swift. The one i am making is for her graduation. I need some songs to put in the video of pictures. I want it to be sad and slow like those songs. She loves country like Taylor Swift, Miranda Lambert, Lady Antebellum, Keith Urban, Brad Paisley, Gloriana, etc.