Get right down to the soil line and do not be afraid of taking out the odd bit of healthy grass. It also loosens up your muscles so you'll be in shape for the baseball and football television season when they roll around again in a few weeks. A lot of you want to roll your lawns with something heavy and round. This is a bad thing for the soil that supports the grass. Rolling the lawn compacts the soil, making it more difficult for the turf grass roots to penetrate into the soil.
Soil compaction makes it harder for the grass to grow and thus easier for the weeds to compete.
The only thing that rolling does well is to flatten out any bumps in the lawn. Mind you, a stiff raking will accomplish the same thing. Lose the lawn roller. Turf grass thrives on the same kind of soil found in gardens. Rich or fertile, well drained loam is best and soils that are high in organic matter tend to grow the best grass.