Zone? Estimated budget? Your gardening skill level? How much time do you want to put into maintaining it? Agree the concrete bricks aren't ideal, but it's important to keep the grass out of a flower bed, or maintenance will be a pain.

Chicago, Illinois is located in USDA Hardiness Zone 5 and Zone 6. $300 budget using existing plants and adding additional color flower perranial. Low maintanance. Thank you Jakkom.

Is there more yard on the other side of the front walk? Both sides should be considered in a design.

Is the planter a raised bed? You would need to replace the brick with some type of edge to hold in the dirt.

Trellis on the brick wall behind the planter, in front of the planter, and big fence for privacy.

If the lawn isn't much more than what is shown in the picture, remove the brick and turn the entire little lawn into a front garden.

Here are a few suggestions: