It depends on the type of bond. Most bonds are paper bonds, and bought at half the face value, in this case $25. It is currently 2010 so it should be fully matured, since it has been 12 years. Bonds change interests almost every year, so one year may speed up the maturing process, while another slows it down. But congratulations to you because you now have a $50 bond to cash in. Spend it wisely.
