When making or expanding a garden spot in a grass covered yard, your hand shovel is actually much more helpful than the rototiller. My experience is that tilling sod may look easier, but it ends badly. This is because the sod must be flipped over – Green Side Down, in order to get a good clean start on your yard garden. In gardening terms, grass is an aggressive, unwanted, tenacious, destructive, irritating weed! It can greatly reduce the productivity of your plot. If you rototill, small pieces of grass roots will be exposed to sunlight and quickly grow back, with a vengeance. You will not be happy about the final result. Turning the sod completely over, so that no green can be seen, cuts it off from sunlight and keeps your grass from becoming a problem. Flipping the green side down also converts grass and weeds into helpful under-garden compost. Each year I turn the grassy sod and leftover weeds upside down by hand, exposing the clear soil for conditioning and seeding. It gets me out of the house for some exercise and a good garden "fix". After flipping the sod, I use a garden weasel tine tool to grind the dirt for easy seeding. There is a trick to rolling the shovel so that no green can be seen......here is a video demo:
Hope you have a great garden this year!