In my family we have known of a coat of arms in our name for some time, so I was surprised to find that Amazon was selling bags, sweatshirts, etc. with a very d

In my family we have known of a coat of arms in our name for some time, so I was surprised to find that Amazon was selling bags, sweatshirts, etc. with a very different coat of arms also attributed to my family name. After some digging, I found out they are using a military insignia given by the king to one of his noble captains with my name. The insignia would be something like a flag to identify his army on the field, So I guess there are many uses for coats of arms. I have much to learn about heraldry, I'd appreciate any references I could read.