If you die without a last will, formally referred to as dying intestate, the state will decide how your property is distributed. In community property states, this means that your community property will be given to your spouse/partner. Any property you owned in joint tenancy would automatically go to the joint owner, and any property held in trust would go to the beneficiaries — subject to the spouse/partner’s share in some states. Any property in your name alone would go to the persons named in your state’s laws.
Keep in mind that each state has its own laws about intestancy, but in general your property.