It looks like a bunny that's been scratching their ear a lot. Our Big Bunny had this and it turned out to be a fungal infection in his ear. Mites is also a definite possibility, as is an ear infection. Those often throw up some yellow waxy stuff like I think I see in the picture along with being irritating to the point that a rabbit will worry the inside of their ear to the point of making a small wound. Best to have it checked out, with cytology done on the crusty stuff in that ear to identify the pathogens.