So the bible verse states:

out of the mercy seat made he the cherubims on the two ends thereof.

That's pretty clear. So he made the cherubims from the mercy seat.

Also, before jumping to conclusions, Ezekial states,

20 These were the living creatures [that had 4 faces] I had seen beneath the God of Israel by the Kebar River, and I realized that they were cherubim

So if the living creatures, that had four faces, are cherubim, does that mean that all cherubim are living creatures, with four faces.

As an example, all apples are fruits, but not all fruits, are apples.