Here's an easy to make and care-for miniature garden that you can make to brighten up your home or workplace. You can put this together using materials that you can find in your household, backyard, and/or neighborhood.
I used a candy tin, similar to an Altoids tin, as my container. I thought that it was cute and compact at first, but I did overlook the fact that it might rust over time. I would suggest looking a glass or terracotta dish first choice, but if you do use a metal container, you may want to line the inside with plastic.
Gravel, or other rocks for drainage material:
Because your container probably won't have a drainage hole, you'll want to fill it with a bottom layer of some rocks to make sure that your plants won't be soaking in water. I collected some gravel from my backyard; pea gravel would also be good because of the small scale of this project.
I would recommend using clean potting soil if you have any on hand versus digging up a bit of dirt from your backyard to make sure that it's pest free. If you do the latter, be sure to check for worms or any other wildlife before using the soil.
You can usually find some moss in shady, moist areas as ground cover or growing on rocks and trees. When you find a nice lush patch, you can use a shovel to lift up a chunk of moss, including that the soil it is bound to. Try not to pull up too much more than you need if you're taking some from the wild or some place that isn't your backyard :) Also be careful when harvesting moss from a tree, as ripping bark off of the tree could damage it.