There are two types of fiber in food, water soluble and insoluble. The insoluble type doesn't break down totally and you can see pieces of those food in your stool. You are more likely to see food remnants in stool if your food is not chewed well.
Nuts and seeds are a type of insoluble fiber so you might see pieces in stool. This is totally normal. And we all need to eat insoluble types of fiber to keep us from getting constipated.
People with IBS usually have one of two types, either diarrhea or constipation [IBS-D of IBS-C].
Stool texture varies from person to person AND will vary in ones own body due to what we eat. For example, I am normally quite "formed" but if I eat a meal with fried foods or high fat content, I get fluffy floaters. If you go to this link, it will show you the Bristol Stool Chart that shows a variety of stools and what it means.
www.webmd.com/digestive-disorders/poop-chart-bristol-stool-scale