I have a very small back garden. Every year I do something different. Ask me "So what is new and exciting?" and I will tell you more than you ever wanted to know about Bees.
You can grow Things to Eat and Flowers in the smallest space. If you are new to gardening and/or tend to be neat and like structure, you may find The Ultimate Guide to Square Foot Gardening of use by George Gerona. George has made his article comprehensive and his blog Loyal Gardener is one of the best gardening blogs I know. Or you may plant a Spiral Garden. Or grow vegetables in a pipe.
Even I dream and plan. You have to plan. Ever grow too many Zucchini? No? Never do that. Your neighbors will only absorb so much Zucchini before they run when they see you coming.
This year I am adding two new Herbs, lovely blue Borage to attract Bees and an exotic Oregano used to make a condiment called Zaatar to sprinkle on my Hummus. It is so worth it to grow Herbs. I thought I hated Oregano until I grew some and tasted the dried Herb I grew myself. Nothing like that dessicated stuff in the supermarket.
Every warmish sunny day I am outside staring prayerfully at my Texas Star Hibiscus and hoping for that first shoot. I planted it last Summer. It is said to be hardy but it has been a long snowy Winter here in Philadelphia. Even in Texas they pamper it. We shall see. No room in a row house garden for sissy plants.
Last but not least, I am excited about the Three Sisters garden concept, so I am going to squeeze in one of them somewhere. Squash tends to spread.
I have too much shade from neighboring back gardens. So maybe I will have to borrow a garden? And so my fevered garden dreams grow and go.