My grandpa used to have a worm box in the ground with a screen below it where he grew worms for bait. He put all of his coffee grounds in there. Always had plenty of big worms for trout bait, not sure if the coffee grounds were for food or to make the bait better. When we went fishing he always carried around the worms in some of that coffee ground dirt in a Sir Walter Raleigh pipe tobacco can that I still have.