\documentclass{article}
\usepackage{tikz}
\begin{document}
\begin{tikzpicture}[rounded corners,ultra thick]
\shade[top color=yellow,bottom color=black] (0,0) rectangle +(2,1);
\shade[left color=yellow,right color=black] (3,0) rectangle +(2,1);
\shadedraw[inner color=yellow,outer color=black,draw=yellow] (6,0) rectangle +(2,1);
\shade[ball color=green] (9,.5) circle (.5cm);
\end{tikzpicture}
\end{document}