Mencken, H.L. 1921. Columbia Encyclopedia World Factbook Columbia Gazetteer American Heritage Coll. The American Language. Dig dug dug Note 26.
Bin is the correct American pronunciation.
Bean, as we have seen, is the English. Be, in the subjunctive, is practically extinct. Burned with a distinct d- sound is almost unknown in American. Bust has quite displaced it. Cotched is heard only in the South, and mainly among negroes.