Answer: Hymenolepis nana, the dwarf tapeworm
The diagnostic features are its short length and characteristic proglottids, as well as its classic eggs with inner and outer shells. The inner shell has polar filaments emerging from it (arrows below), distinguishing it from H. diminuta, which does not.
Here is a poem for this case from Blaine Mathison, parasitologist extradordinaire:
There once was a kid from Indiana
Who with his oatmeal did like banana
But with his food he did eat
A most wonderful treat
The cestode known as H. nana
If you google "oatmeal" and "bugs," you will find multiple consumer complaints (and some nice YouTube videos) to explain the oatmeal reference!