Off & on, I have offered the Toyboys & Phineas kale. Nice, curly, green kale.
Cagney & Bezukhov initially showed interest as it is green & leafy. They would even go as far as to nibble it so the smell clearly did not put them off (unlike mint). However, a little nibble is all they would partake of before apathy set in & it was completely ignored.
Phineas has also shown an interest in the curly green vegetable. He also has a nibble but his nibble is larger & more sustained than the Toyboys, almost to the point that I have wondered if he actually likes it.
(Click on photos to enlarge)