looking for information on a 1939 series postal savings system certificate number 8454. i think its a bond.?

IT IS FROM ST. PETERSBURG, FL(22ND ST. STATION) it is a one dollar. issued date june 10,1954. date when interest begins-july 1,1954. it is a certificate of deposit. please help me find its value or information on it. it was left to me by my great great uncle.