24c Winfield Scott
(read how to identify your stamp below)
You have the 24c Winfield Scott from the years 1870-1873. It is uncommon. The stamp was issued with a grill (as shown below) embossed on the stamp, because stamps with this grill are so rare I have not referred to it.
It is 99.99% likely that you have the version without the grill. To find the value of the stamp click here.
This stamp was reprinted in 1875 and it can be viewed by clicking on the numbers 167-177. These are all accounted for, so you will not own this.