Name: Sandy B. Ford River Twp, Michigan UP (Zone 4b) (Zone 4b-maybe 5a)
They made me think of the Yin-Yang bean, too.
There are a couple of varieties on this page https://www.abeancollectorswin... that look similar to yours, particularly the "Red Marbles" a little ways down the page.
“Think occasionally of the suffering of which you spare yourself the sight." ~ Albert Schweitzer C/F temp conversion