Aesop Rock
Really digging Holy Smokes. The backing tracks on Skelethon remind me of stuff by Odd Nosdam and Tobacco (but they focus on ambient/psych synths rather than vocals). I posted some stuff by Tobacco a while back including a track featuring Aesop Rock actually
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As far as bluesy/folksy metal goes, here's some interesting stuff. Weedeater has some really laid back interludes between their heavier tracks. Dopethrone is a smoldering mass of DOOM STONER METAL. Satan is smoking a bong on the album cover. You get exactly what you see. I've posted plenty of Grails before, but it's relevant. They float around between post-rock, stoner/doom shit, and blues. Reincarnation Blues is baller as all hell. Also some Witch Mountain 'cuz they have a really strong blues/hard rock thing going on. Some of the band members are part of SunnO))) and you can totally tell. It's much more listenable than 30 minute long tracks of guitar drone and screeching bird vocals that SunnO))) puts out on their own though.
If you like blues or folk and don't get grossed out by post-rock Grails is really good stuff. The band members switch instruments between songs and they throw shit like a banjo into the mix just for shits and giggles. Great dark atmospheric acoustic background music to play while you skin a deer or grind grain into flour by hand or something. I dunno man I'm drunk. Listen to Grails.