The following object description includes basic information from the Dublin Core Metadata Initiative (DCMI). An additional notes field is included to list dates from the actual letter, envelope postmark locations, and any other identifying details.
While Jack does not explain how much money the bond was worth, I would be interested to look into the war bond records (if those are still available) and see if I could find documentation about the bond that he purchased.
I also find it very interesting that Jack does not inform Margaret about his purchase of the bond until it is already in the mail, and he essentially only informs her of it so that she can send it to him.
War Bonds were available to be purchased, and functioned similarly to a loan for the Federal Government. People would purchase a bond, thus essentially allowing the government to borrow money, which would be paid back with interest at a later date. This was a solid exchange for people who purchased the bonds, as they were in place to receive more money back than they had put in.
enroll.nationalww2museum.org