Could it be eczema if you have a couple of reddish brown coin-like shaped marks on your chest and they really itch but sometimes are dry?

The symptoms you describe, including reddish-brown coin-like shaped marks on your chest that itch and sometimes become dry, could indicate eczema. Eczema is a common skin condition that causes inflammation, redness, itching, and dryness. The exact cause of eczema is not fully understood, but it is thought to be related to genetic and environmental factors. While I can't diagnose your specific condition, it would be best to consult a dermatologist or healthcare provider to receive an accurate diagnosis and appropriate treatment.