I wasn't aware that Starbucks has a program where you can pick up free coffee grounds to use as fertilizer your garden. It's fantastic for acidity-loving plants like blueberries, and deters lots of garden pests like slugs and ants. Just don't overdo it or it'll change the pH of your soil pretty drastically. Ask at your local coffee shop - Starbucks or otherwise - I'm sure they wouldn't mind handing over something they were throwing out anyway.