I found dark spots (like freckles) on the inside of my 8 -month- old son. he has no teeth and hasn't experienced trauma. what could it be?

Several possibilitie: Dark-complexioned individuals may normally have areas of pigmentation scattered throughout the mouth. But there are more serious conditions that can lead to oral pigmentation, including adrenal insufficiency and peutz-jeghers syndrome. Proper medical assessment is advised.

Location ???: You seem to be indicating freckle like spots inside the mouth, which can be normal pigment variation.It can also represent an autosomal dominant condition called peutz-jeghers syndrome.This includes melanin spots inside the lips, on the mucous membranes & gums along with a tendency to form polyps form in the intestinal tract. I would call this to the attention of your pcp at a regular visit.

Another possibility: ..Is that they are ectopic sebaceous (oil) glands known as Fordyce granules. You really need to have a clinical exam to figure them out, definitively.