Some Betta will eat ANYTHING, so it isn't something to be too concerned about. It seems you are feeding him more than enough, I wouldn't put peas in his diet, it isn't good for their systems, but that is just my opinion.
Remember, Betta don't think like we do, just because we think eating poop is gross, doesn't mean they do. I wouldn't be too concerned, this is pretty normal.
Heck, if it is floating in my tank, Biscotti will eat it. Anything. Earlier today he ate a large chunk of Algae I knocked in while cleaning out the filter. It was gross, lol.