
Hi
I save my coffee grounds(& filter) along with veggie/fruit scraps in an old cottage cheese container.When it is full(at least once a week), I take it out to my compost pile & add it. I turn it now & then to break down the stuff. It makes great fertilizer for the garden!! I also add grass clippings, leaves, egg shells etc, too. A great way to recycle.
I don't know if Dunkin' Donuts gives away used grounds, but I saw that Starbucks does/did. You could ask them if it is only a certain time of the year or year round.