Eating a bit of your own poop although disgusting will not do much harm to your health.
Your poop when you eat it though will cause you a stomach illness and you'll likely vomit and feel really ill and may have symptoms of food poisoning as a result of eating your own poop.
Poop contains bacteria from your intestines that is harmful in large quantities so you should never ingest your poop because it could be deadly if ingested in large quantities.
When my son was 2 years old and wearing diapers he would dig in his diaper and pull poop out of the diaper and eat it.
I took him to the emergency room because he was vomiting and feeling ill after eating some of his poop but the hospital just kept him overnight and pumped his stomach out to clean the poop out.
They said that the amount of poop he ate would not do him any harm but they removed it anyway just to be safe.
He was fine and I had to put him in Pajamas that would keep him out of his diaper to where he could not get access to his diaper.
So eating a small amount of poop is not much harmful but eating too much of the poop can cause severe illness and possible death.