Song from out of the blue

I was down in my music room playing one of my old guitars that I haven't played for a while.  My son came down and got on drums for a bit.  He left and I was playin' some of my more quiet tunes that I wrote.  Kind of in a relaxed mood I guess. 

After a while, I started playing around with some finger pickin'.  Started playing this thing that I had done before and it sounds a lot like an old familiar folk song - still can't recall what it is though.   That got me to playing Walk Right In.  

After a bit, I started fooling around with a C, Em, F, G, C.   Kind of an interesting chord progression.   It started to sound like something I can work on.  So now I need an idea for some lyrics.