I think if I had to pick just one pattern I haven't written to knit from for the rest of my life, it would be the Waffle Hat pattern from Gail Bable. This simple and free hat pattern looks great fitted or slouchy, in every color I've knit thus far -- including solids and stripes -- and works for men or women.
I've gifted this hat to several family members and friends, and know when I'm knitting for charity this pattern will always fit the bill.
I love to share the Waffle Hat pattern with newer hat knitters; just knits and purls along with decreases means knitters with any skill level can make this hat with very little difficulty. I've made the Waffle Hat with worsted weight yarn and DK weight yarn, thanks to the waffle stitch pattern producing a super stretchy hat that will fit any adult using either yarn weight.
This month, as I work through my superwash wool stash for Hats For Sailors, the Waffle Hat will definitely be my go-to. I've already whipped through these three hats this week and have big plans for some purple and grey hats in the near future! As you think about using some of your stash for charity hats, the Waffle Hat is a great first pattern to use -- it works well with any fiber type as well as any color, and you know you're donating a hat that will be well-loved and worn often!