There once was a Japanese Sonic merchandise site.
It is now defunct, and has been gone for years, however...sometimes photos from it will turn up from time to time. When they do appear, Gear tends to get them, as a way to preserve what the person did. This is one of those pictures, and it's all the larger the photo is.
At the top, you can see 4 pin buttons that are probably a set. The smaller one below it may be enamel, or badge-button style. (you can't really tell) The bottom 2 items...well there's no much a way to know what those are either, but they probably have nothing to do with the pins.

The Sega logo/co-branded one might be a post card or possibly a flyer to an event. The yellow background could be a large sticker or a notebook.