Thee Petrucci Music Library is one of the large collections of classical sheet music on the internet. With a bit of searching you can also find some nice folk collections. In Köhler’s Violin Repository of Dance Music you can find a few numbers of Köhler’s The Musical Treasury (1885). In total there’s hundreds of hornpipes, quadrilles, waltzes etcetera. Written for one or two violins, but of course also playable on other instruments.
This is a melodeon waltz I wrote for a musical week on l’Aunay Brûlé in France.