Tip for Keeping Track of Donations

We donate a lot of stuff to various organizations, especially the ones that are willing to come to our area and pick up what we have.
I only recently realized how beneficial it can be to keep an itemized list of the things that you pass along.
It can be a pain to have to document it all on a list, which may be difficult to find each time and to be consistant with, so this year I have started a new system.

When an organization calls to schedule a pick up, I write the name on the calendar, and then I put  post-it in the space on the calendar, making sure that it is dated as well. As I go through things, filling a box or bags, I write down the items on the post-it.
When the group comes to pick up, I just take the post it of the calendar and stick it to the receipt that they leave, creating an itemized record of my donation.

I know that there are digital tools that cnbe used to track such things, and I might do this quarterly or so, but it's easier for me to be consistent if it's right there on the calendar in the kitchen.