If you want to combine 'traditional' and 'political' in the same song, you will have to have a fairly good idea of what was politically important at the time, rather than now. If you feel confident of your historical knowledge there are plenty, especially Scots from around the time of Jacobean Risings. If you are less certain, you might want to explore political-without-specific-people: working conditions, songs written after accidents, and so forth.

A fairly old recording now is 'King Cotton and the songs of the working classes' - a mixture of accompanied and unaccompanied songs. Well worth hearing.