Khepera rolled up the sun (or Ra sitting in the solar boat, if you want to be more specific) from the horizon, and day began. First time ever—not bad.
Nothing New Under the Sun
People were carving scarab-shaped jewelry and amulets in northeast Africa even before Egypt was a country. Because those people didn't write anything down, we can't be sure if these scarabs are also supposed to be Khepera, or even if they mean the same things, but they were already popular long before the Egyptians made them their most common amulet/lucky piece.
Khepera is written about in Egypt's earliest funeral books, of course. Not only does he appear as the scarab of the sunrise, but his name appears again and again in the verbs for "becoming" and "transformation"—the entire reason the Pyramid Texts were written. With the words of these magical spells and prayers, dead kings were able to become spirits and rise up to ride alongside Ra in his boat.
The Sun Trinity
New Kingdom pharaohs put Khepera (in full scarab form) on the doors of their tombs. The artists carved him inside a big circle representing Ra. Along with some other parts, the hieroglyph not only shows all three forms of the sun, but also makes a sort of sentence for "day." Way to save space, peeps.
Big scarabs weren't just used for protecting mummies' hearts, either. Sometimes, kings used scarabs to write out important events and then gave them to people as gifts to remember things by. Kind of like those tourist souvenirs you buy when you go somewhere so you can remember it later.
Double Lucky Bugs
Pharaoh Thutmose III was a popular king, who won many military victories and was remembered as a lucky man for thousands of years after he died. Tiny ceramic scarab-shaped beads show up in tombs even during Roman times almost 1500 years later, inscribed with his name Thutmose and his throne name Menkheperre, which has a big scarab right in the middle of it. Double lucky bugs.
Becoming, Head to Toe
Khepera shows up on mummy cases and sarcophagi/coffins to show the transformation of the dead in the afterlife. Usually you can find him as a winged scarab on the top of the mummy's head or beneath its feet. In later mummies, he also starts showing up across the chest.