Although this website's title is Top 150 Folk Songs Every Kid Should Know there are some good songs for all ages on the list. The first 50 have info and video links but the last 100 on the list is just a list - easier to scroll through.

Some songs which caught my attention are Danny Boy, and The Parting Glass, The Ash Grove, and Simon & Garfunkle's songs Scarborough Fair/Canticle (#45) and The Sounds of Silence (#48).