What foods are notorious for discoloring fecal matter? Will any food do so in large enough quantities?
Beets for one.
I dont really know if its a food but if I take to much psyllium seed husks for a couple days it it takes on the same color.
Red wine always does that for me. Beets too.
Foods containing large amounts of blue food coloring, such as the “Blue’s Clues” apple sauce that was marketed for kids awhile back, produce some very interesing results.
Spinach!
Reports at poopreport.com claim that Faygo Blue Moon Mist soda turns your poop completely green. Makes me wish they sold Faygo in my part of the country…
Carrots, in large enough quantities.
I’m guessing the same holds true for any food chock full 'o carotene.
Iron pills, while not a food, turn it dark or black.
Kaopectate, also not a food, darkens the stools. For me, it might fix up a case of diarrhea but also results in a totally disgusting shade of greenish black. It’s bismuth subsalicylate, which apparently converts to bismuth sulfide. Pepto bismol contains the same ingredient.
Concord grape juice.
My favorite carbonated beverage is Welche’s grape soda…that, and every other grape soda I’ve ever tested = almost bright green.
Tropical Punch Now or Laters once convinced my husband he had colon cancer, until I pointed out his Halloween indiscretions.
And in a related vein, how to change your urine color.
Smoking very strong pot can turn your feces green or gold the next morning . . . or so I’ve been told 
Black Licorice