Where can I find a green wool pea coat?

If you are talking about a US Navy "Aviation" Green Pea Coat, probably a near-by Military Surplus Store. Or for that matter, if you know someone in the US Navy, ask them to pick one up for you at a uniform store.

Here's one in dark green from Victoria's Secret:

Victoria's Secret - Wool peacoat

They have tons more coats, but not all are in green:

Victoria's Secret - Coats