American English: "Should have came ..."

So I’m watching Palmer, and Coles, a white, middle-class US American male, just said I shoulda came and visited you (refering to Palmer, who got out of prison earlier that week). The movie plays in the town of Sylvain, which seems to be imaginary. The actor in question is Jesse C. Boys who was born in North Carolina, so it’s probably a fair assumption that, in ANAE terminology, he is a speaker of Southern.

English isn’t my first language, but I do watch and listen to quite a bit of American English and have never heard such a grammatical construct before. If it was simply part of the dialect, one might expect for it to be quite common, so I’m wondering whether it can be attributed to a sociolect.

To put a question mark here: where did the construction "should(a/have) came" originate and what hypotheses, if any, are there as to why it developed?

(I’m aware of Should have went vs Should have gone but it doesn’t answer my question.)