I'm reading O. Henry The Roads We Take, and there is the phrase, that doesn't make any sense for me.
Shark Dodson got up and leaned against a tree. "I'd a good deal rather that sorrel of yourn hadn't hurt himself, Bob," he said ...
Yourn is a dialect form of yours—it has the same -n affix as mine, which shows up in the corresponding dialect forms hisn, hern, ourn. That sorrel of yourn = That sorrel of yours.
So Shark is expressing a wish ("I'd a good deal rather") that Bob's sorrel (a chestnut-colored horse) had not "hurt himself"—that is, had not been hurt.