In some musical circles you will hear people refer to modes. These are modifications of the way the diatonic scale is played. The major scale is the Ionion mode, and variations of it are assigned different modal names.
The mode name is assigned to the note on which a musician begins a scale. Consider that a scale has notes one through seven before it starts over again in the next octave. Here is a list of modes with the number of the note on which each one starts.
1. Ionion. This is the standard major scale.
2. Dorion. Here is the natural minor key which we get when we play up one step.
3. Phrygian.
4. Lydian.
5. Mixolydian. This is the diminished seventh scale which we get by playing up a fifth.
6. Aeolian.
These will come into play with very old folk songs. The bass chords of the accordion may or may not sound good with some of these modes. Dulcimer players sometimes retune their drone strings when they deviate from the Ionian mode. If you have an instrument with minor chords, try the major chords for the modes that begin on push notes and minor chords for those that start on the pull.