Lightroom - image modify date
When you edit a file LR puts a date on the Metadata
So the Metadata date will be the date of your last edit provided that the Metadata is "Up To Date"
You can also create a smart collect by "edit date" using "greater than", "less than", "equals" or "in the range"
HOpe this helps
|Thunderheads With Egret by Buzz Lightyear|
|Double Rainbow; Abiquiu, NM, USA. by abiquiuense|
from After the Rain