Green Beans are flat
Why do some of my Blue Lake Green Beans end up being flat rather than round? Bush and pole beans.
Washington County Oregon
I found several question/answers in the AaE history. The exact cause has not been identified but one theory is that the Blue Lake pole beans are 'reverting' back. The previous reports have all been for pole beans, this being one of the first that includes bush beans.
If you are saving your own seed, you may be running into some natural hybridizing, but the recommendation is to switch to Kentucky Blue variety (a cross between Blue Lake and Kentucky Wonder.) In another message mentioned finding Blue Lake without a patent # (specifically Ed Hume Seeds.)
From another expert: Unfortunately, the seed stock of the Blue Lake Pole beans became variable and this was the result. The stock has been back bred to regain the proper bean, but not many companies are selling the correct seed as yet. I believe Nichols Garden Nursery in Albany, OR, is and suggest you check with them or any other reputable seed source. If you do have problems in the growing season, you should notify the seller of issues with your crop.
I am probably wrong about the bush beans, please don't use my input as a "new" situation.