On kind of the same note, I've known about the rat poison for awhile now. However, I found this interesting tidbit regarding the origin of Warfarin and its name. Maybe we can just pick a bunch of clover, let it rot, and then eat a handful! Even though Warfarin is created, its origins are just as natural as fish.
"The first oral anticoagulant was developed by scientists at the University of Wisconsin in the 1930s. They noticed that cows that ate spoiled clover had a tendency to hemorrhage. They soon isolated an anticoagulant chemical from the clover and named it Warfarin® to honor the Wisconsin Alumni Research Foundation. The first use of Warfarin was for rat poison: rats would eat the tablets and bleed to death."