Recently noticed a hard knot like bump on my lower chin under the skin, doesn't hurt, bout the size of a pea maybe, what could it be?

Need an exam: An md will be able to help you. It could be a sebaceous cyst, an enlarged lymph node or even a small submandibular gland (salivary) stone or sialolith. An exam is always the best way to understanding. Good luck.

Submental cyst: More than likely it is a lymph gland but swelling under the chin in the midline may be a remnant of embryonic development known as thyroglossal duct cyst. See your doctor . He may want to do an ultrasound. These cysts are usually harmless, but should be removed.