I purchased a small lot of what I thought were fairly valuable stamps from someone who didn't want to take the time to sell the stamps individually. When I bought the lot, I thought this one would be the star, but now I'm not so sure.

This appears to be a Scott #37. The catalog value for a used example of this stamp is $400, and the red cancel would add $40 to that, according to the 2005 Scott's Specialty Catalog. However, Scott #37 is supposed to be perforated, and this isn't. It looks to me as though the perforations were trimmed off for some strange reason.

There is a hinge remnant and a small pencil notation that says "BLL 400" on the reverse.