<canvas width="600" height="400"></canvas>
<script>
    var tela = document.querySelector('canvas');
    var pincel = tela.getContext('2d');
    pincel.fillStyle = 'lightgray';
    pincel.fillRect(0,0,600,400);
    function circulo(x,y,cor) {
        pincel.fillStyle = cor
        pincel.beginPath();
        pincel.arc(x,y,10,0,2*3.14);
        pincel.fill();
    }
    function desenhaFlor(x,y) {
        circulo(x,y,'red');
        circulo(x-20,y,'orange');
        circulo(x,y-20,'yellow');
        circulo(x+20,y,'black');
        circulo(x,y+20,'blue');
    }
    desenhaFlor(300,200);
    desenhaFlor(50,100);
    desenhaFlor(400,50);
</script>