I wanna shiny hunt through breeding, so I just want to know if I can get an Eevee by breeding two Eeveelutions.
Yes, you will get an Eevee from the eggs that you get from breeding a Jolteon and an Espeon.
If I understood your question correctly, then yes. When breeding, the Pokemon hatched will be the original evolution of the female Pokemon, and since you have an espeon, it'll be an eevee.
Source: Knowledge and Experience