Do you have a "family" coat of arms? If so, it may not be exactly what you think. Many people throughout history have used coats of arms ornamentally without giving much thought to the accuracy of their design or their own right to use them. Beginning in the 19th century, the crest which appears on the helmet was mistakenly dubbed a "family crest" by some, and has become an inaccurate synonym for a full coat of arms. In addition, there are many companies in business today who will sell you "your family coat of arms" on a t-shirt, mug, or 'handsomely engraved' plaque. For my husband's surname, POWELL, there is an entire catalog full of such items! While these companies are not necessarily out to scam you, their sales pitch is very misleading and, in some cases, outright incorrect.
Except for a few individual exceptions from some parts of Eastern Europe, there is no such thing as a coat of arms for a surname - despite the claims and implications of some companies to the contrary. Coats of arms are granted to individuals, not families or surnames. A form of property, coats of arms may rightfully be used only by the uninterrupted male line descendants of the person to whom the coat of arms was originally granted. Such grants were (and are) made by the proper heraldic authority for the country in question.
The next time you come across a product or scroll with a family coat of arms for your surname, remember that just because your surname is SMITH, for example, doesn't give you the right to any of the hundreds of coats of arms borne throughout history by others named SMITH. Therefore, how could an individual or company that has not researched your direct family tree know whether you have inherited the right to display a particular coat of arms? If you're looking for something fun to wear on a t-shirt or display in your home, then these items are okay, though misrepresentative. But if you're looking for something from your own family history, then buyer beware!
If you would like to learn if a coat of arms was awarded to your ancestor, you will first need to research your family tree back to the ancestor you believe may have been granted a coats of arms, and then contact the College of Arms or appropriate authority for the country your ancestor was from and request a search in their records (they usually provide this service for a fee). In most countries you can also design and even register your own individual coat of arms based on the arms of someone who shared your surname, or from scratch to mean something special to your family and its history.