Holding neck straight upward, there is a small lump approx. 1 inch above collarbone directly on top of sternomastoid. thyroid or jugular lymph node?

Just a guess: If it's very superficial, likely neither. If directly deep to the muscle, it's probably a lymph node (unless your thyroid is very large). Dozens of nodes are present in the neck, and it can be normal to be able to feel a few. If it's new, enlarging, over about 1cm, firm, or if you have a history of cancer or are simply just concerned, it is never inappropriate to see a doctor (ent, etc.).