pallou Palau has a blue flag with a yellow circle.
Brazil has a green flag with a blue circle inside a yellow diamond.
The flag that is green with a yellow Diamond in the middle of it is the Brizilian Flag.
Kazakhstan has blue flag with yellow sun: http://en.wikipedia.org/wiki/Flag_of_Kazakhstan
The Swedish flag is blue, with a yellow cross on it.
Romania
Red, Green, Blue, Yellow and Black rings on a white field.
Several countries have a blue, yellow, red, and white flag:KiribatiCape VerdeMalaysiaPhilippinesSerbiaSloveniaTuvaluIn addition, the Buddhist flag is blue, yellow, red, and white.
Barbados
The colors are red, yellow, orange and blue. The bottom half of the flag is blue, with an orange star in the middle, and alternating rays of red and yellow in the top half.
The colors are red, yellow, orange and blue. The bottom half of the flag is blue, with an orange star in the middle, and alternating rays of red and yellow in the top half.
Blue, and a number of yellow stars making a circle in the middle.