The song of the week is 'I Can't Feel At Home In This World Anymore' (a.k.a. 'This World Is Not My Home') in the key of G. This song was recorded by the Carter Family in 1931, and since that time has been recorded by numerous old-time, bluegrass, and country artists: some of the bigger names including Bill Monroe, Ralph Stanley, Jim Reeves, Merle Haggard, and Ricky Skaggs.
The chord progression I use for 'I Can't Feel At Home In This World Anymore' is:
Jim & Jesse - key of F
Martina McBride (with Ricky Skaggs) - key of D: not exactly a bluegrass version of the song, but it has good mandolin breaks in it, and is played at a tempo that I prefer.
...but, alternatives for the 2nd line of the progression that I have heard on records and at jams include
Blue Highway - key of G
And, in some versions, line 2 is played one of these ways for the verses of the song, and in a different way for the choruses, with breaks in some versions following the verse progression and in other versions following the chorus progression.
Compare these progressions with Prog. V6 on the Basic Chord Progressions Chart:
...and with the 3 most common chord progressions used for playing 'Leaning On The Everlasting Arms':
1144 1144 1144
1115 11155 1115
1144 1144 1144
11511 11511 1151
'I Can't Feel At Home In This World Anymore' is the first of 3 songs that I intend on introducing into the Intermediate Jam within the next 5 months that has a '2' chord in the progression I use for the song (Notice that some of the alternative progressions for the song of the week do not have a '2' chord in them). The other two songs are 'Homestead On The Farm' (a.k.a. 'I Wonder How The Old Folks Are At Home') https://www.youtube.com/watch?v=82_0ui4taWI (Mac Wiseman - key of A), and 'Cry Cry Darlin' https://www.youtube.com/watch?v=F5ss64M_Z_E (Bill Monroe - key of A. I will lower this one down to the key of G to make it easier for me to sing it.)
Notice in the versions of 'I Can't Feel At Home...' provided here how the harmony part or parts are affected by the presence or absence of the '2' chord in line 2 of the progression. For, unlike the 1,4, and 5 chords, the 2 chord has one note in it that is not part of the major scale. In the key of G, this note is a C#. (The notes of the G major scale are: G, A, B, C, D, E, and F#.) Relative to the G major scale, the number name for the C# note is #4, which is the same note as what would be called b5 (in the key of G: Db) in certain other contexts.
If you find it doesn't come naturally to you to go to the C# note on the 2 chord measure when singing a tenor harmony part for this song in the key of G, try playing the following scale on your instrument: G, A, B, C#, D, E, F#, G until your ear becomes accustomed to hearing the 4th note of this scale in the context of the whole scale. (This is known as the 'G Lydian Scale': in place of the '4' in the major scale, it has a '#4'. The G Lydian Scale has the same notes as the D Major Scale, i.e., it has one more sharp in it than what the G Major Scale has.) The notes of the G Lydian Scale are the safest notes to play on your instrument during '2' chord measures that come up in a song that is in the key of G.
As the jam continues to progress, it is inevitable that more and more songs will be called at it that have chords in them other than the 1,4,and 5. This is happening already at the jam. 4 out of the 17 songs played at the last intermediate jam had one or more of these chords in them. And at the jam before that one, 5 out of the 19 songs that were played had one or more of these chords in them. Until recently, it was uncommon for more than 2 songs to be played at the jam on any given night that had chords other than the 1, 4, and 5 in them, and more often than not, at least one of those songs was either 'Down The Road' or 'Old Joe Clark'.
An informal name for chords other than the 1,4,and 5 that you will sometimes hear in bluegrass circles is 'off-chords'. The '2' chord is one of the two most commonly used major 'off-chords' in traditional bluegrass. The other one is the 'b7' chord. If you have not already done so, I suggest immediately making it a point to memorize the '2' and 'b7' chords for each of the keys that come up at the jam. Remember that '2' is a whole-step higher than '1', and that 'b7' is a whole-step lower than '1':
b7 1 2
Key of G: F G A (A = A,C#,E.)
Key of A G A B (B = B,D#,F#.)
Key of Bb Ab Bb C (C = C,E,G.)
Key of B A B C# (C# = C#,E#,G#)
Key of C Bb C D (D = D,F#,A)
Key of D C D E (E = E,G#,B)
Key of E D E F# (F# = F#,A#,C#)
Key of F Eb F G (G = G,B,D)
In each case, the middle note of the three notes that make up the '2' chord is the #4 note, which when substituted in place of the 4th note of the Major Scale creates the Lydian Scale.
Just as through experience with playing songs that have 1,4,and 5 chords in them, one learns to readily distinguish the sound of the progression 1-4-1 from the sound of the progression 1-5-1, and to detect when a chord is being played that is other than the 1, the 4, or the 5, so also, through experience with playing songs that have various 'off-chords' in them, one learns to be able to just as readily distinguish which 'off-chord' is being played. For starters, I suggest observing that songs that have only the '2' as an 'off-chord' in them tend to have a very different sounding type of melody than songs that have only the 'b7' as an off-chord in them.
Compare the three songs provided here that have '2' chords in them with songs that have been played at the jam that have 'b7' chords in them:
Songs with b7 chords:
Red Haired Boy
Cluck Old Hen
Old Joe Clark
Other songs with '2' chords that have been played at the jam include 'Left Over Biscuits', Old Home Place' (also has a '3' chord in it), and 'Salty Dog Blues' (also has a '6' chord in it.)
Another thing you might notice is that while the 'b7' chord is more often than not sandwiched between '1' chords, just like the '4' and '5' chord most often are, the '2' chord is almost always followed immediately by the '5' chord.
[Those of you who have studied music theory might point out that the '2' chord is functioning here as a 'secondary dominant', and some might not like it that I call it the '2' chord, but that it should rather be called 'the 5 of the 5'. (Rough translation: the chord in question has the same relation to the 5 chord that the 5 chord - a.k.a. the 'dominant' - has to the 1 chord: the '2' pushes to the 5 in the progression, which in turn pushes and resolves to the 1.) But, for our purposes here, and for the sake of simplicity, I will continue to call 'the 5 of the 5' the '2 chord'.]