Certified GKH Gardening Expert
It is very difficult to offer an answer without seeing a photo and knowing the zone, the environment around the plant, the type of plant, and its care.
This symptom can have many causes depending on the type of plant. They can be portions of root, eggs of an insect, fertilizer, eggs of a spider, fungus, among other things.
Yellowing foliage may be unrelated. That is often due to over or under watering.