Perennials are more drought resistant than annuals because their roots go deeper than annuals. No matter what annuals you put in you will have to water until they settle in. Marigolds and portulacca are fairly drought tolerant once established.

If you don't want to water at all then look up Xeriscape gardening. The plants used for this are very drought tolerant, but most are maybe not as colorful as you would like.

Would it be possible to put a rain barrel somewhere near the bed to collect rain water.

Thank you for your suggestions - I do appreciate them so ~ as to your question, is there a rain barrel that would go unnoticable at the end of the road where my flowers are at?

No I don't think there is an inconspicuous rain barrel. When you mentioned the end of the driveway I thought of my son.

My son has a beautiful flower bed at the end of his driveway around his light posts He used small shrubs perennials and grasses in good soil. It seldom gets watered except by the rain or by hand if there is a long dry period. He got advice on what would work there from his local greenhouse.

I am a big fan of going to local growers. They grow their own plants and are knowledgable about what will work in specific situations and in your area. The advice is worth the visit and their plants are often better than you can buy at big box stores where the employees don't know plants or how to take care of them.

When I lived in Zone 6 I had a bed near the entrance to my driveway that was difficult to water unless I wanted to drag 200' of hose there (NOT!). It was a triangular shaped bed and at the "point" was a clump of miscanthus "Morning Light". In front was a mixture of tall verbena (verbena bonariensis) and "Bright Lights" cosmos. The verbena had purple/blue flowers and the cosmos was a mixture of yellow and orange.

The first year these were planted I did water the seeds/plants to get them established. Then they were on their own and what a sight they were. Wish I would have had a digital camera then so I could post a picture.

In years thereafter, both the cosmos and bonariensis self-seeded. All I did was weed out the excess seedlings and never had to water.

I will warn you that the bonariensis is a PROLIFIC self-seeder. However, the time spent in the spring removing excess plants was worth it because of the show the combination produced the rest of the growing season.

Some that have been drought tolerant for me are annual rudbeckias, california poppy, and airy larkspur.

Coreopsis, cosmos, galliardia, clarkia, senecio, and "chia" sage are all drought tolerant for me in LA.

Larkspur self-seeds in a dry area for me. Cosmos also does well without watering. This year am trying Emilia coccinea (Flora's paintbrush) in a VERY dry area as I have read that it likes dry soil. I have a cat named Flora - I hope she enjoys them.

You know, there are rain barrels out there that are shaped like urns or olive jars. If you design the planting so that the barrel is a feature in it, it really could work. Gardeners Supply has a very attractive one. I saw one shaped just like it at Sam's last week. I'm including a link for you to a list of all their barrels.

That being said, here are some annuals and bulbs that I find to be fairly drought tolerant.
Salvias: farinacea, leucantha, and guaranitica. They are tender perennials, but are easy to grow as annuals.
zinnias
rain lilies (Zephyranthes: these are bulbs. Candida is the most attractive in foliage.)
Cleome is pretty tolerant of dry conditions too. The above listings are all good, with exceptions noted below. I would give a big amen to portulaca.

If you google 'Texas Superstar' you can find lists of plants that are quite drought tolerant and have received awards for growing in heat, drought, and humidity.

It's important to note that although all these plants will tolerate somewhat dry conditions, none will survive without some water. Be sure to incorporate plenty of organic material into the soil (peat moss is excellent for retaining moisture) and use plenty of mulch around them too.

FYI, larkspur and California poppies are strictly cool weather plants. Here, in central Mississippi, they are pretty well shot by late June.

Here is a link that might be useful: Rain Barrels