Local Government Code §116.054

(a) A county depository may pledge with the commissioners court as security under this subchapter: (1) a bond, note, security of indebtedness, or other evidence of indebtedness of the United States if the evidence of indebtedness is supported by the full faith and credit of the United States or is guaranteed as to principal and interest by the United States; (2) a bond of this state or of a county, municipality, independent school district, or common school district; (3) a bond issued under the federal farm loan acts; (4) a road district bond; (5) a bond, pledge, or other security issued by the board of regents of The University of Texas System; (6) bank acceptances of banks having a capital stock of at least $500,000; (7) a note or bond secured by mortgages insured and debentures issued by the Federal Housing Administration; (8) shares or share accounts of a savings and loan association organized under the laws of this state or of a federal savings and loan association domiciled in this state if the payment of the share or share accounts is insured by the Federal Savings and Loan Insurance Corporation; or (9) a bond issued by a municipal corporation in this state. (b) Securities provided under this section must have a total market value equal to the amount of the depository bond.