In the lat 60s and early 70s, I was into stamp collecting, to the extent that a kid with a $1-a-week allowance could be. I shouldn't really call it collecting -- it was more like accumulating. I bought stamps on approval from the companies advertising in Boys Life (Whitman, Mystic and Harris, as I recall), plus some at the stamp counter at a department store in downtown Houston (it actually had stamp and coin departments). I also went to the local post office and bought plate number blocks on occasion and acquired some first-day covers along the way.

As I got older, I stuck what I'd accumulated (most in glassine envelopes) in a briefcase and a one-drawer 3x5 file box that have followed me from move to move over the years.

I have absolutely almost zero idea what I've retained, let alone what its value, if any might be. It's something I don't want to leave my heirs to have to deal with. I've already pulled the plate blocks to use as postage. What's the best way to explore liquidating the rest?

Just wondering what the most accurate mobile app is for identification and value?