First off Amanda you need to go and talk to the city or county department head that is responsible for the citation and talk to them about what you can do to accomplish your objective of having a naturalistic landscaping while conforming to city/county code so that you will not have to deal with this again.
This is very important as it will let them know that you are living there and are attending to your property though you may not be currently in compliance with code.
Make the contact tomorrow if possible or an appointment to go over the citation. One possible outcome is that they can give you more time than the seven days to deal with your situation. Be prepared to offer a timetable that your own schedule will allow and one that is reasonable.
Good luck.

Depending on the size of the area, you might try putting some type of boarder around it. Or even put up a sign saying that this is a native planting.

It's possible that the marshal in your area may be acting on regulations based on fire risk. Sometimes certain native plants and grasses can be at risk of fire, particularly in naturally hot, dry areas of the U.S., such as California or possibly your area of Texas. I second the advice about talking to the city or county. Maybe you can ask if the regulations are based on fire risk, or simply some kind of "quality of life" visual issue. If they're just basing it on a visual issue, hopefully you can come to some kind of compromise that incorporates these important native wildflowers and grasses.

I also second the advice about adding a border. We maintain the original lawn that came with our house (which we mow in the customary way) but also have native "areas/gardens" marked off by rock borders. I kept some of the natives growing in these areas, but also intentionally planted some additional natives that bloom at various times throughout the spring and summer, so that the "native areas" look more like intentional flower gardens.

Not sure where you are in Texas, but you may find some helpful information and support from the Native Plant Society of Texas (see link below) or the Lady Bird Johnson Wildflower Center at the University of Texas in Austin:

Lady Bird Johnson Wildflower Center:
http://www.wildflower.org/plants/result.php?id_plant=SACO5

Good luck!

Here is a link that might be useful: Native Plant Society of Texas

Thanks for the suggestions. My boyfriend went ahead and mowed the area anyway when he got home from work (he was like, "I knew this would happen!"... he was always skeptical I would be able to "get away with it").

So we're up to code for now, but I hope the salvias and other plants grow back, and if they do, then I'll be back to the same problem.

Adding some kind of border sounds like a good idea, to make it look more like a garden. I'm new to this, but I assume it will take a while to get a good stand of attractive plants, but in the meantime it needs to look good and not like I just didn't feel like mowing my yard.

I'd also like to add some more species that bloom at different times so I'll always have something blooming, but right now I've only been trying to nurture what was already there. I guess I could always just to the buffalograss thing in the front yard and forget the wildflowers, but it seems like a shame to waste what nature's already given me.

Oh dear, that is too bad the salvia in your yard has been mowed.

I think it's definitely possible to have a native garden that looks acceptable to the "lawn police". Hopefully the salvia will bounce back, along with some clumps of the native grasses.

Try making a border, and that will allow the salvia and some of the natives to regenerate undisturbed, but in a way that looks "orderly". We created our rock border during the process of planting the natives on the land we live on just by using rocks that we dug up while planting things. You may have some nice rocks down there under your soil, or you can buy rocks or a low fence from a landscape supply place.

The Texas Native Plant Society or the Lady Bird Johnson Wildflower Center may also be able to let you know where to find native seeds or plants native to your area if you decide to add some additional native plantings.

You can also try talking to your local Cooperative Extension. They may have helpful info, and/or may be able to shed some light on the regulations and citations in your area, and ways to stay in keeping with regulations but still maintain natives in your landscape.

Sorry about being late here.
In Wimberly we used to mow around the wildflowers in bloom.
So to keep the meadow looking nice and still taking small steps to keep it attractive. I have been through the citation deal. Someone has to complain before they will
send you the warning. I found out who reported me (the
person who turned me in never knew that I knew who they were). We began a dialog to preserve what we wanted and
to help them understand why we did it and have been report free for 2 years.
Art

Wild Ones is a good place for information about "weed laws" and other such things. As advocates for native plants they know a thing or two about dealing with the public on these matters. Check out their website for some helpful info.

Here is a link that might be useful: Wild Ones

Oh, I'm sorry you are having problems with ordinance! Depending on what sort of community you live in, though, a meadow-type wildflower garden may not be appropriate. The critters that like to make use of those habitats are animals that many people living in cities or suburbs or towns consider "pests." Most of us don't want our neighbors increasing the population of mice and insects that live in colonies, for example.

I have had great success by planting native perennials, shrubs, and clumping grasses (like Little Bluestem and Switchgrass) in a more traditional-styled garden, which in my area means mulch and rocks and stuff mixed in with free-standing plants. So while I am using prairie grasses, and prairie flowers like coneflower, I'm planting them in the way that people normally plant gardens; in tended beds with defined borders. The birds love it, and it's nice to see seed-eaters like goldfinches clinging to flower heads while insect-eaters like robins and sparrows hop around in the mulched area.

I leave the dead seedheads stand all winter and they are quite dramatic in the winter landscape. I mix in some shrubs and small trees (all natives), including some berry-producers that different birds love. I do have one area that's currently weedy and is too steep to really plant in a formal way, and I plan on putting in a lower-growing grass (I'm thinking of giving prairie dropseed a try) with a small sprinkling of perennials, and I can just weed-whack the whole thing down in the fall.

I must admit that while I'm a big fan of using natives and gardening for wildlife, as a city-dweller I honestly don't really want a meadow right next door to me. I think many people feel the same. So I think the idea of leaving defined areas standing with an edging border (and maybe a few nice lawn ornaments or a sign) is a good one.

Sorry for your problems. Do you live in an urban/suburban area? Unfortunately, if you do, you will probably always have this problem, as they do have ordinances in these areas and nosy neighbors. Most people who live there want cookie-cutter yards that adhere to their view of beauty. Wildflowers are weeds to them and also they do draw/hide critters that they don't want around. That's one reason why we moved to a rural area with residential/agricultural zoning. Plus we are surrounded by woods and what we have in our yard can't be seen very well. Not only can we view nature to any extent we want, we also don't have to look at any others' houses, cars, etc. and they don't have to look at ours. It's heaven. I only wish we had done it 25 years ago instead of 5.