Could be an attached memory or sentimental value, whatever.
Conventional worth be dammed.
Given to me it would either be the quilts my grandmother made, or the charts my grandfather followed along with during the moon landing.
Personal items would be the assorted thank you notes the elderly have given me from being in retirement industry. Want to make a collage of them one day.
Whoa, now; I suggest you take a peek at the quilt market. Old quilts in good condition can demand astonishingly high prices.
Photos & letters all fall into this category, I think. I suspect that some future historian might find some value in them, but if we don’t extictify ourselves, there’s so much digital material - photos, videos, emails - that anyone studying any period after 2000 is going to be doing a much different job, involving much less sleuthing, than those who studied ancient periods.