FB message from a supplier, Great Lakes Staple Seeds, who has them--FOR FREE:
Hi Clyde, thanks for reaching out about the Kurzer's - funny you should mention popping pods - earlier today I was working in the seed room and kept hearing intermittent pops that had me puzzles - turns out they were the lima pods popping before I got them threshed! Thank you for letting me know you appreciated the letter - I am a geek for seeds and their stories and was especially excited about Kurzer's.
The letter mentioned, linked on his Kurzer's seed page, is a hand written PDF file from Douglas Kurzer, telling the story of the bean, and how he came to have it...and that nobody, even him, originally wanted the seed!
I haven't grown these Lima Beans, but that has happened to me with Scarlet Runner Beans. I usually save the seeds from those year to year with good germination. The bean seed is SO pretty!