Windmill?

[Darkfire]

For the windmill: unless you want it to be moving, you can simply make it of already present-in-the-game-models. It may suck though if you let the player go near it.

For the scarecrow... It should be possible like that too. For example, take some sticks and make a cross out of them. Then cover it with grey flags (they're in /entity/ornament, I think) from both sides. Put some head-thingy on top. That's the toughest part- maybe agrippas head? However, you would need to make a non-item version of it (it's fairly simple). Than a hat (the wooden bowl) and maybe some hands ?
And so you have a scarecrow. A shitty one, but still. Unless you go for a creepy version: scarecrow made out of human parts. Then it's friggin perfect.

Ps. Well, as I said, this way of doing things has no chance for animation/movement and is quite corny. Hope I helped though ;D