I found this circuit inside a LED reflector that turns on and off at regular intervals, and there is this white circle in it. I am guessing that it somehow keeps time of the intervsle, but can someone explain it to me? Also, I found this same circle on another device with 3 LEDs that turn on and off in regular intervals.
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John A.
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It appears to be a Glop Top or Chip On Board (COB) type of assembly. However a black material is usually used:
Instead of packaging the integrated circuit into a leaded case, the actual integrated circuit is placed on the Printed Circuit Board (PCB) and bonded out:
Go here for more about COB and the source of these images.

st2000
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It looks like a resin 'blob' covering a component, most likely the IC responsible for controlling the LED.
Resin is usually used to protect components from moisture, heat, mechanical stress, dirt etc, and sometimes to conceal them.
It could be the same as this

clabacchio
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