I am 30 and currently 15 weeks pregnant and noticed left supraclavicular lymph nodes palpable very slightly enlarged. Can these nodes be swollen from a cold? A physician noted they were palpable before

If it is truly. A left supraclavicular lymph node, it could be an infection in the head/neck area, chest, or even abdomen. With your pregnancy, imaging might be a problem, but please show it to a surgeon or infectious disease specialist for an opinion.
Stable? If the enlarged node has been stable for months, i would not be concerned. But if it is getting larger, i would consider a node biopsy in the absence of any obvious diagnosis.