Add the letter "s" to the end of druther, and that's the noun form. It means preferences. For example, If I had had my druthers, I would have gone down the less travelled road with Robert Frost. As is, it can be used as a verb meaning would rather. For example, At the fork in the road, I'd druther take the less travelled road with Robert Frost.
Druther's was created in 1963.
"Druther" is merely a slurred version of "I'd rather", especially in regions where the dialect results in "rather" being pronounced as "ruther." (I'druther) Thus, when someone says "If I had my druthers..." they are referring to what would be their preferences: "If I could do what I want to do, I'd rather do this".
It means having what you'd prefer-- "Druther" is a slurring of "I'd ruther" (a pronunciation of "rather")," as in "I have to go to school, but I'druther [I would rather] go to a party"