Who Am I? The One Who Laughed.

I was an old woman when the Lord appeared to my husband. Our tent was pitched by the "oaks of Mamre." when this happened. This visitor told my husband that I bear a son. How could I bear a son when I was well past the prime childbearing years. When I heard what they had said, "I laughed to myself." Later when I denied having laughed when the Lord asked my husband why I had laughed.  There are not too many places in the Bible that talk of laughter but when I did it might have been the first time it was recorded in God's Word, the Bible. Who am I?