In most California Home Owner’s policies there is workers compensation coverage for casual employees. If you and your friend have a contract, then your friend would be responsible for any work related injury suffered while cutting your grass. You can submit a claim for any injury sustained on your property. The amount covered will be limited by the policy. There are at least two other sources of coverage in the homeowner’s policy, the medical payments section and the legal liability section. The company will adjust the claim using these provisions.