One spring evening in Ridgefield, Wash., Chad and Rachel Hamar walked onto the Clark County Amphitheater stage as 18,000 spectators sized them up. Four songs later, they left that stage to waves of cheering and applause, plus a lot of puzzled people turning to their friends and asking, “Who the hell was that? And why haven’t I heard of them before?” The answers were simple. Chad and Rachel were and are partners in music and in life. And this gig, opening for country music icon Kenny Chesney, was only the second time they had ever played as Cloverdayle.