I would recommend downloading the Official Unity PostProcessing stack (https://www.assetstore.unity3d.com/en/#!/content/83912) and turning on Ambient Occlusion to improve the look of Low Poly models.

All pieces are <600 polygons.

Full list of all 81 models:
- Bar
- Beam (Base)
- Beam (Horizontal)
- Beam (Vertical)
- Bench
- Bridge (Stone)
- Bridge (Wood)
- Bush (Variation 1)
- Bush (Variation 2)
- Bush (Variation 3)
- Bush (Variation 4)
- Bush (Variation 5)
- Cart
- Cattail
- Chimney (Variation 1)
- Chimney (Variation 2)
- Door (Variation 1)
- Fence (Wood, Variation 1)
- Fence (Wood, Variation 2)
- Flower (Variation 1)
- Flower (Variation 2)
- Flower (Variation 3)
- Flower (Variation 4)
- Flower (Variation 5)
- Grass (Variation 1)
- Grass (Variation 2)
- Grass (Variation 3)
- Hatchet
- Lily Pad (Variation 1)
- Lily Pad (Variation 2)
- Log
- Moss (Wall)
- Moss (Wall, Half)
- Moss (Door)
- Moss (Window)
- Mushroom (Variation 1)
- Mushroom (Variation 2)
- Mushroom (Variation 3)
- Pickaxe
- Pitchfork
- Rock (Variation 1)
- Rock (Variation 2)
- Rock (Variation 3)
- Roof (Straw)
- Roof (Wood, Variation 1)
- Roof (Wood, Variation 2)
- Shovel
- Sign
- Stone (Variation 1)
- Stone (Variation 2)
- Stone (Variation 3)
- Stool
- Table
- Tree (Variation 1)
- Tree (Variation 2)
- Tree (Variation 3)
- Tree (Variation 4)
- Tree (Variation 5)
- Tree (Fallen, Big)
- Tree (Fallen, Small)
- Tree (Stump, Variation 1)
- Tree (Stump, Variation 2)
- Trough
- Wall (Stone)
- Wall (Stone, Corner)
- Wall (Stone, Door)
- Wall (Stone, Window)
- Wall (Stone, Half)
- Wall (Wood, Variation 1)
- Wall (Wood, Variation 1, Door)
- Wall (Wood, Variation 1, Window)
- Wall (Wood, Variation 2)
- Wall (Wood, Variation 2, Door)
- Wall (Wood, Variation 2, Window)
- Wall (Wood, Variation 3)
- Wall (Wood, Variation 3, Door)
- Wall (Wood, Variation 3, Window)
- Wall (Wood, End)
- Well
- Window (Variation 1)