Upon opening the imaginary inbox to read the Tractor’s calendar email yesterday afternoon, I almost had an accident. Right there at the desk. Because two of 2010’s heavy-rotation best-of-list abounding artists — for me, at least — are coming together for one show, on a tiny stage in Ballard, and it’s my humble opinion that Seattle proper should literally be beside itself with excitement. Sweet-throated alt.indie.crooner Jessica Lea Mayfield is heading out on tour with none other than last year’s Prince of Make-It-Hurt-So-Good Nathaniel Rateliff.

Neither of these artists needs an introduction, but in the event that you’re not familiar, Daytrotter has radical sessions from each of them up on their site that will give you a good taste of their respective sounds. {Jessica’s is here, and Nathaniel’s is here.} While they share a common undercurrent of soul-bearing earnestness, JLM — who will be headlining the night — has a catchy, sexy, post-folk type of sound that contrasts nicely with Nathaniel’s straightforward harmony-loaded achecore. She’s traded her campfire sing-a-long undercurrent from the last release for a little-black-dress-sometimes kind of sound, and it’s really winning for her. (If you want to play along at home, listen to the studio cuts “For Today” and/or “Kiss Me Again” from With Blasphemy So Heartfelt, and then hop on over to her website at http://jessicaleamayfield.com for a free download of the new single, “Our Hearts are Wrong.”) It could be a next-album kind of maturity, or perhaps a different producer — but whatever it is, her vibe has definitely shifted and started a new course.

If that isn’t enough to send you running for tickets, take note: she’ll be getting the room warmed up by Nathaniel Rateliff, whose name can we can barely type without inserting a metaphorical swoon/faint. Not because he’s some kind of dapper, debonaire ladykiller or anything like that — but because the full frontal heart-on-his-sleeve storytelling that’s consistently woven through his songs puts some of the ‘earnestcore’ bands that have been hitting the bar of late to utter shame. (And PS, we’re talking about the bands we really like.) Songs like “Shroud” from the Daytrotter session and about two-thirds of last year’s stellar release In Memory of Loss are enough to take the most stoic, emotionless anti-everything hipster out at the knees with barely a glance. If you’ve got the inclination, his go-to tracks from IMoL are “Once in a Great While,” “Early Spring Til,” and “Whimper and Wail,” but frankly, the album as a whole is worth your hard earned money.

Let’s put it this way: If there is one set you go to blindly this year on the notion that someone else told you it would be good, this is it. I’ll even go out on a limb here and state that Nathaniel’s got the potential to show up the headliner, but let’s hope for her sake that it vibes like more of a split bill than a flip-flopped slot. (See also: every show that the Head and the Heart played in Seattle during the second half of 2010.)

Tickets are on sale now, and even though the show isn’t until May 3rd,you’d be wise to pick some up now. Based on the spouting of converted uber-fans (and speaking as a double-winner myself), this night will sell out.

{Photo courtesy of Victoria VanBruinisse, from Nathaniel’s set last August at the Triple Door with Pearly Gate Music. Where we all sat in the front row of booths and sobbed, but in a good way. 9p / 21+ / $12.}