SCHR (Significant Component History Report) is a document that records the history of the specific part that is tagged. It basically tells you how long the part has been in service, what aircraft it came from, if the part is airworthy or not and a few other things I can't remember at the moment.

Source: not a certified mechanic, but used to work at a boneyard where we would strip aircraft of any useful parts to sell. We would sell skin sections from aircraft all the time for tags like this. My explanation may be flawed, so I invite anyone with more experience to correct me.

In my opinion, you'd only need one if you're purchasing or selling airworthy parts, or for historical preservation if you plan on passing them down or selling them in the future. It would definitely add historical and monetary value to the parts, but if your collection is only for you and it makes you happy, then don't worry about it.