Sign Canvas Corrugated Metal 2x1
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 (19 POIs)
Hybrid Mining (tier 5), Hybrid Energy (tier 4), Olgiddy & Brother Advertising (tier 4), Downtown MeltDowns (tier 3), Pawsnout Factory (tier 3), BONG Auto Parts Manufacturing (tier 2), Hybrid Energy Substation #2 (tier 2), Hybrid Energy Substation #3 (tier 1), Mausoleums (tier 1), Motel Seven (tier 1), Navezgane Civil Defense Shelter (tier 1), Hybrid Energy Substation #4, Hybrid Energy Substation #5, Leap's Faith, Massive Gains Mall, MeltDowns, Power Distribution Station #1, Power Distribution Station #2, Sapphire Square.
Points of interest built with this block (any of its variants), the highest tiers first, from the game's prefab files.