Please explain if it is possible to get a tumor on the roof of your mouth?

Yes: Yes it is possible. Not real common. Most common is benign bony growth in middle called a torus. See your dentist if you are worried/suspicious. Good luck.

Definitely, yes: Lumps or tumors on the roof of your mouth are often benign and easily treated, but sometimes can indicate a more serious condition. See your dentist for evaluation and excisional biopsy for proper diagnosis.