Q.Are These Dutch Iris ?
There’s an annual argument with my 2nd wife over these plants. I want to keep them ’cause I transplanted them from my Mom’s acreage just after Dad passed. I’ve had them for 25 years or more. Because they have expanded from the original half dozen bulbs to an area about 3 x 5 feet,& grow to 4ft. tall the wife says they are NOT Dutch Iris. … Help …

Certified GKH Gardening Expert
After comparing your photos with other iris varieties, it looks more like a spuria iris. Dutch iris have three standards and three falls. Your flower and the spuria have the extra petals above the falls. See what you think:
https://wiki.irises.org/Spec/SpecOrientalis
https://jcra.ncsu.edu/resources/photographs/details.php?serial=364168
https://plants.ces.ncsu.edu/plants/iris-hollandica/
But you certainly should keep a plant transplanted from your mom's yard. It probably could use dividing. :)