A couple weeks ago I volunteered to help clean up a park near downtown LA, Vista Hermosa Park. With budget cuts they can't keep their full maintenance & upkeep staff. It seemed like it was close to work but I had never seen or heard of it. When I got there is was a small but beautiful park! It's like a hidden oasis with dirt paths, a little pond with a waterfall, and this gorgeous view of the skyline.
We helped out weeding some of the areas in the park. I met some really cool people and I would definitely recommend volunteering there on the third Saturday of every month. It was only 3 hours so you can enjoy the rest of your day.