With the smell of cheese curds and nearby cow fields wafting through the divinely cool summer air, My Morning Jacket's frontman Jim James sounded pleased that his band went a little out of the way to play to Twin Cities indie-rock fans Friday night.

"I feel like a child at the county fair," the woolly bearded singer/guitarist commented a half-hour into a two-hour performance at Somerset Amphitheater, where his Kentucky-bred quintet topped a blue-ribbon triple bill also featuring Band of Horses and Minnesota's own Trampled by Turtles.

The first big concert of the year at the revamped outdoor venue in Somerset, Wis. -- where last month's SoundTown festival was abruptly canceled due to poor ticket sales -- Friday's show had its share of ups and downs just like the rickety amusement park rides of James' county-fair dreams.

An ungodly long beer line (yes, "line" singular, which was the problem) and a logjam of traffic in Stillwater marred the out-there experience for many of the 5,000 attendees. Just the fact that a lot of them arrived via Stillwater's single-lane lift bridge was a sign that Friday's show was loaded with many Somerset first-timers. Metalheads headed there for Slipknot's Knotfest next weekend will surely know to cross the St. Croix River at Interstate 94 instead.

Too bad more fans weren't there in time for Friday night's most solid set, a fast-cranking 50-minute blast by the all-acoustic Trampled by Turtles. Having bounced around the festival circuit all summer, the Duluth-bred string pickers sounded as well-greased as the nearby farm tractors. Fans who did show in time greeted them like headliners, too, verbosely singing along to the new singles "Walt Whitman" and the finale "Alone" and dancing like wildfire mid-set to the hyper-picked "Wait So Long."

Band of Horses' hourlong set didn't go so smoothly. Frontman Ben Bridwell twice stopped mid-song to quick-fix his guitar (the rest of the band thankfully kept playing in both cases). He also yelled out instructions to roadies during another tune on how to fix a malfunctioning amp: "Just whack it" was his sage advice.

It's only rock 'n' roll, and Bridwell's crew often resemble another garage-twangy Horse band, Neil Young's Crazy Horse, on playing it loose for the sake of playing it right. The Seattle-reared group certainly hit all the right notes early on in the aptly chosen opener "The First Song" and another oldie, "Weed Party." At set's end, they rode off into the sunset in grand style with the serene hit "The Funeral" and the maximum-powered "Northwest Apartment."

The final full-tilt montage in My Morning Jacket's set was even better, but boy, oh boy, did those good ol' boys hit a low, lulling valley point mid-show before winding up on the mountaintop. Long, sparkless, arty jams such as "The Day Is Coming" and "Touch Me, I'm Going to Scream, Pt. 2" wore on at a wounded-horse's clip, and the long saxophone solo in "Dondante" did nothing to spur on the crowd. Things were much more exhilarating before and after that, though.

Before, the heavy dirge of "Holdin' on to Black Metal" sounded even heavier, and a pair of 2003-era gems brought the set's first half to a climax, "I Will Sing You Songs" and "Mahgeetah." After, the band roused the audience in the encore with a trifecta of anthemic rockers, "I'm Amazed," "Anytime" and "One Big Holiday."

The most memorable moment, though -- one that burned brighter under the starry, campfire-ready night -- came at the start of the encore, when all five members of Trampled by Turtles joined MMJ on the elegant ballad "Wonderful (The Way I Feel)." No way that song would have come off so magically cooped up indoors somewhere in town.

See each band's set list at startribune.com/artcetera. Chris Riemenschneider • 612-673-4658 Twitter: @ChrisRstrib