If the coin is as you describe, and has VICTORIA DEI GRATIA with no other wording and the "young bust" with the year below it, your coin is very possibly a Halfcrown dating between 1841 to 1864. The faint hints of a circular pattern is probably the remnants of what was a fairly ornate crowned shield. If your coin is as worn as you suggest, it will not be worth much. A reputable coin dealer will be able to assess your coin more accurately.
circular
By pattern, I'm assuming you mean relationship. The radius is half the length of the diameter.
Circular flow means the pattern in which goods,services,and resources flow in the marketplace.
It travels in a circular motion.
convection cell
You don't need to, circular needles can be used like straight ones--just pretend the cord isn't there ;)
When something has symmetry in a radial (circular) pattern.
A window with a circular geometric pattern.
In level countryside ,pond ,bank etc houses are built around such a feature that they develop a circular shape.
i think these are winds
Circular path of water around the hill.
The circular pattern in the middle of the Indian flag is called the Ashoka Chakra. It is a navy blue wheel with 24 spokes, and it represents the eternal wheel of law.