Help Us Solve a Mystery

I have already posted this in the heirloom forum, and am posting it here, too, since it is so busy:

Alright you plant sleuths, is anyone familiar with "Prairie Home Companion" and Garrison Keillor? I just finished reading his book "Lake Wobegon Days". In it, he refers to a canteloupe called "Dauntless Dukes", and 40 lb.watermelons called "Big Bertha" as being standards grown in the area of Lake Wobegon. We have been unable to unearth even a hint as to whether these are real varieties, or fictional, and can't find them anywhere. We are very interested in receiving any information on these, and acquiring some as well, if possible. Thanks for the help