Had lump at back of neck left side under hairline for a year,recently its got bigger, size of a kidney bean. its firm and quite hard, feels round.

Lymph node: There are thousands of lymph node located around the body that help screen out germs in the body serum. There are many in the neck, head & behind the ear. At rest these are often 1/4 inch in diameter (pea sized) and may grow to marble sized when reacting to a stimulus. Bug bites, or viral infections can increase their size.What you describe is normal.If concerned review this with your doc.