Make a Button in two steps

Final view

Step 1:
Create new file and fill background with black color (Shft+f5 ---> color ---> Select Black color---> OK).

select Elliptical Marquee Tool and Draw a circle. Press and hold 'Shift key' while Drawing circle. because it will results to accurate..

Select Gradient fill Tool and select the two color combination, here I've choose "FFFC00" and "A5A300" colors.

Hit OK. And drag the cursor from top-left corner to right-bottom.

Step 2:

Again select Elliptical Marquee Tool and Draw a circle smaller than previously drawn. Press and hold 'Shift key' while Drawing circle. because it will results to accurate..

Again select Gradient Fill tool and Drag cursor from Right-Bottom corner to Left-Upper corner..

Done..!!

Tutorial for creating Simple pattern in Photoshop..

Create Simple Pattern

Final view

Step 1:
Create new file (50px * 50px) with white background.
Go to View ---> Rulers..

drag the cursor from rulers to the middle of the layer from both sides..

Step 2:

Select the Left-upper-half square with Rectangular marquee tool and fill it with black color.
(Use shft+f5 ---> color ---> Select Black color ---> OK).
Now select the right-lower-half square with Rectangular marquee tool and fill it with black color.