Pick Pockets . . . I made the striped one a while ago and gave it to a daughter. She never used it, probably misplaced it, so I asked for it back. Then I made the larger one for the metal finger picks and the smaller one because I liked the yarn. The other daughter is getting the striped one and the blue/green pair is for me.
They are meant to hang on the tuning pegs so your picks are always ready and available.
There is a pattern available on Ravelry for knit Guitar Pick Pouches but it is priced at $5 which is a little much for something so simple. I just made this up as I went along.