Zia...

"This banner is based on the New Mexico flag. The yellow field and red symbol colors are the colors of Spain. First brought to New Mexico by Spanish explorers in 1540. On New Mexico's flag we see a red sun with rays stretching out from it. There are four groups of rays with four rays in each group. This is an ancient sun symbol of a Native American people called the Zia. The Zia believed that the giver of all good gave them gifts in groups of four. These gifts are: 
The four directions - north, east, south and west. 
The four seasons - spring, summer, fall and winter. 
The day - sunrise, noon, evening and night. 
Life itself - childhood, youth, middle years and old age. 
All of these are bound by a circle of life and love, without a beginning or end."(http://www.50states.com/newmexic.htm)
Other sourses say instead of the four times of the day it is the 4 sacred obligations of the Zia people: clear minds, strong bodies, pure spirits and devotion to the welfare of the tribe

"The official state flag of New Mexico was chosen from a flag competition in 1920 (the competition was held to replace an older New Mexico flag). The winner was Dr. Harry Mera, a doctor and archaeologist from Santa Fe, New Mexico. Dr. Mera's design is an interpretation of an ancient Sun symbol called a Zia (this symbol was found on a water jar made in the late 1800s in Zia Pueblo). Since four is a sacred number for the Zia, there are four rays coming from each side of the stylized Sun. The colors red and yellow are used because they were the colors of the flag of the Spanish conquistadors who went to New Mexico in the early 1500s. New Mexico was the 47th state in the USA; it was admitted in 1912."
(http://www.enchantedlearning.com/usa/flags/newmexico/newmexicoflag.shtml)