A few months ago, the widow of a dear hunting/fishing buddy gave me all of his gear. Since I live in the desert, I can't use some of the fishing tackle that was primarily for Northern species like walleye, lake trout and char (left over from trips to Canada)

I would like to try to donate some of it to a worthy organization. Any suggestions?

You may not want to go to the trouble, but I'd suggest selling it on ebay, depending on what you've got, in small lots that would fit in a small flat rate box. Then donate money to charity of your choice or the NRA.

If you don't want to do it, find a relative or smart neighborhood kid that will do it for say 25% of net, then donate the rest.

there is a guy on 360tuna.com that uses tackle & fishing trips as incentive prizes for students & others who supply gear & fishing trips to Vets.
try contacting member Pope or just post about your situation.
( I moderate a couple of DIY forums on 360T )

FWIW