My favorite bands with folk metal influences (I don;t want to say folk metal bands because some of these bands aren't folk all the time):
-Alestorm: folk/power metal album with lyrics about pirates or similar topics. Fast and catchy, with funny lyrics and vocals. Check out drums on their first albums, they are incredible!
-Amorphis: I only heard their latest 3 albums and Magic & Mayhem. Folk is used only sporadically, but I know they used it much more on previous albums...
-Emir Hot: not really a band, and there's only one but great album. Folk is also used only sporadically, mainly balkan folk with accordions...
-Ensiferum: first 2 albums are amazing, totally filler-less. Victory Songs is a good album although not as good as first two albums. I tried to like From Afar but it's pretty boring...
-Finntroll: not really a fan of this band, but their latest album is pretty good. Solsagan is an amazing song
-Korpiklaani: their first album is magnificent, without any kind of fillers. After that album they are only getting worse...
-Turisas: their first two albums are fantastic mix of folk and symphonic metal. Their 3rd album is mostly symphonic with only sporradic folk apperances...
-Týr: first 4 albums could be classified as progressive folk metal but they don't use any folk instruments. Their 5th album marks a change in bands style which is now more powermetallish...
-Wuthering Heights: I haven't listened to their first 2 albums, because I heard that those are mostly uncatchy progressive metal albums (not a fan of the genre). Their 3rd album is FANTASTIC. Imagine Blind Guardian making a folk metal album with Dio singing. Their vocalist Nils Patrik Johansson must be Dio's son or something. I don't really like their 4th album, but their 5th (Salt) is amazing, full of catchy choruses, fast and folky parts. Lyrics are also amazing. CHECK THIS BAND OUT!