It shall be lawful for banks, savings banks, trust companies, insurance companies, personal representatives, administrators, guardians, trustees, and other fiduciaries, the State of Nebraska and its political subdivisions, and institutions and agencies thereof, to invest their funds and the money in their custody or possession, eligible for investment, in bonds or notes secured by mortgages insured by the Federal Housing Administrator, in debentures issued by the Federal Housing Administrator, and in securities issued by national mortgage associations.