I have a lump on my collar bone and was told it's lipoma, should I get a biopsy?

It depends. A lipoma, a benign fatty tumor, has a characteristic feel. It is squishy, rubbery, and moves easily under the skin. A doctor diagnoses a lipoma by feel, location, and absence of other symptoms. If the lipoma doesn't grow and isn't causing symptoms, most doctors leave them alone. If a lipoma grows or becomes painful, an ultrasound or biopsy might be needed.
Probably not. If it has been examined and was felt to be a typical lipoma and it is not changing or causing any symptoms, you should be fine just leaving it alone.