This was billed as a Portuguese kale, but it does bear some resemblance to the coleworts, as seen here in _the numbering at Bethlehem_ by Pieter Brueghel in 1566.
It is interesting to note that 40years later Nathaniel Bacon painted large-headed cabbages in his _cookmaid with still life vegetables_
Also of note, Sylvia Landsberg uses collards to 'stand in' for coleworts at the Bayleaf Hall gardens (rather than omit this important plant due to insure ties as to it). And Dierdre Larkin at the Cloisters agrees. Plimoth Plantation also uses collards as coleworts.
I have collards too, as they were from seed they are not so photogenic yet. It will be interesting to compare them.