No, they don't have special names.
It's not that hard to create simple custom shapes in a graphics program.
The "Add to Cart" button is entirely CSS. The more elaborate graphics are images. Some rather impressive graphic shapes can be created with CSS only; however, images are still the mainstay for more elaborate patterns and textures.
You can copy images from most web sites easily enough. Over time, you can amass your own collection of shapes. You can Google a class of images such as "halloween" or "christmas" but I don't know of a way to Google particular shapes.
Maybe a graphics person can offer more insight, though. There are several graphic regulars here who may add some experience to the topic.