Are USB or flash drive considered flash memory?
USB is good for a backup "at hand", but you have to think that an USB stick breaks too easy. Paper is still best.
(Also you have to create the txt file directly on the USB, offline, then archive/password protect it, and all this ideally from a live OS).
My mom is a meticulous person. Even if I cleaned it myself, she would still clean it thinking that there are still some stuffs that are unfixed.
You have to find better places. Keep the seed in a sealed envelope and write on it "important". Or write it onto the back of a diploma. Or onto the last page of a book. Or all 3. Also, you don't have a shelf that's only yours? That can also be a good place. However, on the desk, no matter it's under the mouse pad, it's bad place from start.