I've checked every page of Albert's button-book for you. No match found. Though there are several types of "crossed-cannons" buttons, none have a number on them. Therefore, it doesn't seem to be a US-gov't military button, nor Confederate. I think it's very unlikely to be a military-school button. That leaves State Militia, or Foreign.
I'm leaning to Foreign, due to a vague 20-something-year-old memory about the crossed-cannons-with-number emblem being World War 1 French Artillery. But I feel no certainty at all about that.
Is it a two-piece or one-piece button? Because you made no mention of a backmark, I assume there isn't one. Info about the button's back-side (and a photo of it) would help us to help you.
Regards,
TheCannonballGuy