Decor and furniture
Sign Canvas Corrugated Metal 6x1
It's a sign. You write things on it.
Harvest drops
Iron× 10
Taken apart with a harvesting tool (axe, pickaxe, shovel), before perks and tool bonuses.
When it collapses
Falling, it leaves 
Scrap Metal Pile (60% of the time) where it lands.
Where to find (7 POIs)
Flushing Rule Palace (tier 4), Happy Sleep Motel (tier 3), Le Spank (tier 3), Savage Country (tier 3), Maggie's Corner Cafe (tier 2), Buffalo Blues Building, Shabby St. Outlet.
Points of interest built with this block (any of its variants), the highest tiers first, from the game's prefab files.