Autumn leaves are plentiful, free, and excellent for use in the organic garden.
Good straw mulch is a good thing for an organic garden.
Bark mulch is decorative and functional; win-win!
Wood chips can be a cheap and abundant mulch material.
Free grass clippings make excellent mulch, too! Ask your neighbors for theirs!
Salt marsh hay is something of a regional mulch material.
Compost is both a mulch and a fertilizing amendment.
There are many benefits to using pine needles as a mulch, including cost and erosion control.