What does a normal breast ultrasound look like in a healthy person?

Black&White&Gray. Normal breast tissue will look gray on ultrasound; near the nipple, it is common to see ducts which can have a honeycomb pattern. Most importantly, cancers look very different than normal breast tissue. To the untrained eye, ultrasounds are like a rorschach test--you can see what you want to see in them.
Pictures tell story. A "normal" breast ultrasound(us) will look different depending on the age of the patients and breast density. It is hard to describe in words. I recommend speaking with the technologist and radiologist on your next exam and ask them to review the images with you. Typically a 34 year old should not need breast imaging unless there is a problem or you are a part of a high risk program.
No abnormalities. A normal breast ultrasound should show no abnormal architecture of the breast tissue, no solid or cystic masses, no cluster of calcifications (which are generally a marker for underlying cancer), or localized signs of tissue swelling.