I've read about using hay or 'spoiled' hay as garden mulch. Is this ok. Where...
You can use hay as a mulch. However, there is the possibility of introducing weed seeds.
For sources you can look in local newspapers or possibly a farm supply store.
See Other options for mulch in a vegetable garden http://extension.umd.edu/growit/food-gardening-101/step-5-taking-care-your-garden#weeds and in landscape beds http://pubs.ext.vt.edu/426/426-724/426-724.html