Years ago, when I was young, energetic, unemployed and BC (before child) so I had time, I thought to inventory my fashion pattern and fabric collection. At first I cut a piece of fabric and slipped them into photo slide sheets with yardage amount and put them in a binder. That way I could check for matches I needed for the garment. You just never know when the perfect match would be found. Folding out this binder in the fabric store was imbarrassing, so I put the pieces on safety pins and on rings- that also got cumbersome, and dirty. After a few months, I gave up on the idea and just took what I wanted to match with me. Or bought it anyway and added to my stash.
Skip, maybe 20, years; quilting started and collecting started all over. For the first 10 years I could tell you when, where, why, how much, cost & who I was with.
Then I started art quilting & I bought 1/2 yd by the dozen or more and lost track. I have 1000's. When I want to make a quilt I pull out up to 200 pieces, shuffle and reshuffle, reshelve and get out more.
Do I need to know----that is the question...... The hunt is part of the fun. So NO, I don't know and don't care. Works for me.