It sounds like you mean the lumps or cord-like bumps on a vein , which are often caused by a varicose vein or a superficial blood clot in a surface vein. A vein that feels hard, red, warm, or tender can be superficial thrombophlebitis , which should be checked by a clinician, especially if the pain is new or worsening.

What it might be

  • Varicose vein: enlarged, twisted vein that can look or feel lumpy under the skin.
  • Superficial thrombophlebitis: inflammation and clotting in a vein near the skin surface; it can feel like a firm lump or hard cord.
  • Less common causes: irritation after an IV, injury, or other vein problems.

When to get urgent help

Seek urgent care now if you have:

  • sudden swelling in one leg.
  • chest pain or shortness of breath.
  • severe pain, spreading redness, or fever.

Those can point to a more serious clot or infection.

What you can do

  • Rest and elevate the area.
  • Avoid heavy pressure or massaging the lump.
  • Wear compression if a clinician recommends it.
  • Get evaluated if it is new, painful, or persists.

TL;DR: “Mounds of dirt in a vein” probably means a lumpy or cord-like vein, most often a varicose vein or a superficial clot, and a painful or warm one should be checked.