After two decades, The World Famous Grassholes are among the most storied bluegrass bands in Maine’s well-stocked country-music history, with dozens of collaborators who have made their way through the band and four well-received albums. For the past decade, however, the current five-piece lineup of Heather Kahill (fiddle), Merrill Marsh (guitar), Flann O’Brien (bass), Sam Pfeifle (guitar), and Field Rider (“deadly” banjo, according to one Dublin nightclub owner) have taken the band to new heights, with four-part harmonies in the traditional style infused with contemporary songwriting that draws from pop to indie rock, to punk and the blues. Their latest album, “Gently Used,” produced with Jonathan Wyman and Chris “C$” Burns, takes you on a journey from a burning Monroe-style picker in “Walk Right Out”, to an Eagles crooner in “Colorado”, to the strutting blues of the Mickey Newbury classic “Why You Been Gone So Long.” You might find something better to listen to while the sun sets on a warm summer afternoon, but you’ll have to look hard.