I'll give my favorite consultant's response, "That depends."
There's no such thing as a generic group of amateur folk musicians. Each group has its own personality, style, and repertoire. If you join up with a group of hard core old-time enthusiasts, they might want nothing but squirrelly crooked modal fiddle tunes. Get together with some Irish session musicians and it'll be jigs and reels played faster than most humans can think. Associate with folkies and it might be old Dylan and new Griffiths.
Decide who you want to play with and find out what they are playing.
Better yet, at this point don't worry about what others are playing. figure out what you all want to play. Develop your own style, personality, and repertoire.