Sorry it took me so long! I got distracted by life. My mother guessed the correct answer - they were marker tips. (although she shouldn't be allowed to win since she is with him almost everyday. My cousin, Rachel, was the first runner up and she should be considered the actual winner) .
This is why Lily is only allowed to use the markers during Jamison's nap.
It was actually a relief to find those tips on the floor. For weeks I thought he was ingesting the tips. As in, sucking the ink out of them and then just swallowing them. So it was very reassuring to find those tips scattered in corners of the room and under chairs.
You can see that five of the six the above markers were "Color Wonder" markers. So those tips were clear. But it's the other markers (like the above grey one) that have caused the big problems. The black and the red markers give me the biggest scare when he rounds the corner. The other colors just look ridiculous.
These little guys feel victim to the biter as well. I thought he'd like to color with these friendly looking crayons. Within minutes both were de-crayoned.