This 2c Columbian cover is in dreadful shape, but I still like it.

It was mailed from the National Bank of Cold Spring, on Hudson in Putnam county, New York, on June 5, 1893 to Reuben B. Gilbert of Mahopac Falls, New York.
Inside were some canceled checks written on Mr. Gilbert's account in
1892:

Perhaps originally there were very many canceled checks in the envelope (maybe for all of
1892) with copies of Mr. Gilbert's bank records.
In any case, the envelope was overweight, assessed 4c postage due and stamped with a straight line "POSTAGE DUE 4" marking with "cts" in manuscript black ink added.
On top of this marking, two Scott #J23 2c postage due stamps were affixed and canceled.
So despite that this cover is very worn and dirty, the neat combination of a Columbian 2c commemorative with postage due stamps makes it charming and full of character to me.