Ask Mr. Smarty Plants

It would help to know something more about the plant.   Is it a woody plant?  What sorts of leaves does it have?  What is its habitat?  Without that information it was difficult for me to feel that I had chosen plants that were similar to the one you found.  However, below are a few suggestions for plants with lilac-colored flowers that are native to Webb County.  Some of them are reported to have scents.  For the others I could find no information about the scent.  They range in size from about 1 foot to more than 5 feet.  If you found your plant in a flower bed or lawn, it is very likely it is not native to North America and is an imported cultivated plant and, as such, won't appear in our Native Plant Database.

Guajacum angustifolium (Texas lignum-vitae)   Here is more information from Aggie Horticulture.

Dalea pogonathera (Bearded dalea) is reported to smell like licorice if bruised.  Here are photos and more information

Astragalus nuttallianus (Nuttall's milkvetch)

Lippia alba (Bushy lippia) is strongly scented.  Here are more photos and information from Aggie Horticulture.

Lythrum californicum (California loosestrife)   Here are more photos and information from Southeastern Arizona Wildflowers and Southwest Environmental Information Network.

Pluchea odorata (Sweetscent)    Here are more photos and information.

Leucophyllum frutescens (Cenizo)

If your plant is one of these, the information about its attraction for butterflies and hummingbirds will be under the heading "Benefits".  Observation will also tell you if butterflies are attracted to it.

If none of these is your plant and you have photos, please visit our Plant Identification page to find links to several Plant Identification forums that accept photos for identification.