Not a locomotive, but a cool story:

http://www.bikeme.tv/index.php/buried-treasure/

Restorable?

Hard to tell from the photos how extensive the rust really is. There have been many vehicles of all sorts dug out of the mud in Eastern Europe and Russia that were later restored. The cold climate and lack of oxygen in these areas sometimes preserves vehicles in a "frozen" state as though they were buried yesterday. Would be nice to see a picture after the bike was cleaned up.

Unless I'm more than usually mistaken, there is at least one 'club' in Russia that restores and operates verious kinds of tanks that have been recovered this way.

There's been a lot of nonsense online about WW2 tanks pulled from bogs out there and immediately fired up and driven off. Utter foolishness to even think that was possible.
Yeah, they've yanked more than a few WW2 tanks (mostly Russian T-34s and various tank destroyers) outof some of those bogs but the engines and transmissions on those tanks could be pretty tempermental when they were brand new. Transmissions especially were problematic in Russian armor in that timeframe.
And as for German stuff, well, they broke down all the time as well. Today the general idea is that German armor was surperior, when in fact it was only so for firepower and armor. They broke down almost constantly, which made it tough for the Germans who often pillaged their Ordnance crews to become infantrymen and then nobody was left to fix them. That's why many German tank types were captured intact and fully tested soon after they first appeared on the battlefield...

Hans von Luck in his memoirs mentions chucking all kinds of material into German bogs and lakes on the (shrinking) Eastern Front as things were winding up in April '45. This is neat stuff, though I think I would be cautious about taking spade to signal indication with so much ordinance lying around.

We lost a distant relative in a French hedgerow in the '70's. She was burning brush and lit something off ...

Just an FYI, there's no "I" in Ordnance. Sorry, I am a former Army Ordnance officer and it drives me nuts to see it spelled incorrectly so often...
But case in point on what might be underground: http://www.bbc.com/news/world-europe-26654314
I've been there, there are signs on every road into the area, saying the farmers dump unexploded rounds into the ditches then call the local EOD unit to come get them when the pile is high enough. Tourists are warned not to touch these piles. Amazing that 100 years later, farmers are still turning up shells from the same fields they've been tilling all this time. They pretty much shelled the Flanders sector constantly from 1914 to 1918. The place looked like the surface of the Moon when they were done.