Field sandbur (Cenchrus incertus) is an annual warm season grass that has nasty little burs enclosing its seeds. It often grows close to the ground allowing the stems to root at the nodes. It can also grow upright which sometimes tricks people into thinking they have two species.
Field sandbur reproduces each year by seeds then spreads horizontally. The leaf blades are usually flat, twisted or folded, 2" — 5" long, and have very short hairs on the surface that are visible with magnification.
Field sandbur prefers dry sandy soils but tolerates a wide range of soil textures. It is often found in cultivated fields, roadsides, lawns, washes, and disturbed areas at elevations ranging from 100' — 6,000'. It is a native of the southeastern U.S. but has spread west with the help of agriculture and commerce.