Many of my neighbors dispose of their trees’ leaves in the fall, then pay for bark or wood mulch to spread in their flower beds in spring. I collect the leaves (and some from one neighbor’s yard) and use them as mulch, which seems more logical to me. Leaf mulch suppresses weeds well and doesn’t seem to support the growth of artillery fungus like wood mulch does, at least in my experience. Like any mulch, it’s more effective in shaded areas than in the sun. In the photo, I applied them near the northeast corner of my house, under the big rhododendron and next to the foamflower (Tiarella cordifolia).
My lone remaining honey locust tree doesn’t produce much mulch for me because its leaflets are too small to pick up and quickly decompose into the lawn. My neighbors’ oak and maple trees produce plenty of leaves and the wind distributes them to my yard, where I’d have to rake them up anyway.
Leaf mulch probably breaks down more quickly than wood mulch, so I apply it every year, which happens to be how often the trees produce their leaves. I collect it using my lawn mower with its bagging attachment. The lawn mower picks up the leaves fairly efficiently, chops them a bit, and compresses them into the bag. Once placed, the partially chopped leaves don’t blow away.