They are aged for sure, but you can see the deep purple spore staining on both caps.
The dark anulus or veil remnant is as you say dark purple to black, and that too is from a heavy dusting of spores.
I have found cubes that appear almost purple because of the spore distribution due to prime conditions.
Cultivated cubes I have seen tend to be much cleaner of course, but they tend to lack the heavy dusting of spores that you will see in some wildcrafted specimens
What Glaukus said. You've got 9 or so old ones to be sure there - looks like they have seen some sun and rain for at least 2 days me thinks. More mature as you rightly say. Slice them down the middle to check for maggots in the cap where it meets the stem.
The purple spore colour can be found on cubes that are in a clutch with others or straight up on their own as apparently they can somehow generate their own wind believe it or not, cbf finding a link to back that up though.
Worth remembering that with cubes one of the most defining features is the veil remnant which is the dark fringe around the stem half to three-quarters of the way up.
Always best to leave them in the ground if you are taking pics though, because of course no-one around here would actually ingest them
