One thing that always arrives with summer is the appearance of farmer's markets. And one thing that always comes with farmer's markets are leftovers! Ask a vegetable stand at your farmer's market about donating their unsold veggies, scraps, or even unusable parts (carrot, radish, beet tops) to your local shelter's rabbits. All you have to do is transport the goods to the shelter, as often as you like. It's an easy way to give a shelter bunny a healthy meal for free. Make sure to relay which veggies are okay, and which to avoid (ie tomatoes, beans, potatoes, rhubarb; and use carrots, bananas, (anything with high sugar) sparingly).
Atlas Farms has been donating their delicious organic vegetables to the Boston MSPCA for a few weeks, and it's turning out great for everyone involved. See pictures below for proof! (All of these bunnies are available for adoption through the Boston MSPCA; click on their names for additional information.)
Piper & Widget (Guinea pigs need greens too!)
Another idea: If you're baking/cooking with strawberries and have a ton of strawberry tops, save them in an airtight container and take them to your shelter. Strawberry tops make for a delicious treat!
Thanks for thinking of helping out a shelter or rescue in your area!