Mexican Stamp ID Help Please

I'm not a world-wide collector, although I have some stamps from all over that I inherited. I've found the stamp pictured below, it's (obviously) on an envelope, letter inside is dated 1880. But I have no idea how to ID the stamp. Any help? I am (more than likely) going to put it on ebay, so if you have an idea of its value that would be awesome to know as well (especially if it's a one-in-a-million find, ha ha).

Thanks in advance!
Dave

In order to ID the stamp you can always try http://stampworld.com . If I am correct, the overprint on it signifies the district in which this particular stamp was purchased.


Peter

Hi, 1879 Scott 125 1.50$ or 1882 Scott 133 6.00$ depending on the paper.
You might get 5.00$ for the cover.It's way down in the listings as far as rare Mexican stamps go.If it had a blue cancel it would be worth much more..Link below to William Smith Herndon who was more interesting than the cover!
https://tshaonline.org/handbook/onl...ticles/fhe32

link too the main catalog
http://library.si.edu/digital-libra...eofsta00coll

Thanks!