iKnightly
I mean 'do we know of any instance when matter/energy was created?'
It depends. If you mean locally, then no. Energy is conserved everywhere in the sense that if one looks closely at any region of space and time (duration), no energy is created there. The law of conservation of energy is really a local statement: for every infinitesimal region of spacetime, as much energy flows out as flows in. It has never been violated.
If you mean globally, i.e., "if look at the total energy of the universe, can it change in time?" the the answer to that is either "sort of" or "you can't do that." It's not that humans can't carry out the experiment to measure a "total energy" of the universe; it's rather that there may be no coherent way to define it in the first place (and as far as I'm aware of, when there is, it's always conserved).
On the other hand, cosmic inflation has the property of expanding space while maintaining constant energy density. In some sense, one can view it as 'creating energy', although some would disagree, preferring to say that gravitational energy balances out the change. There is some room for a disagreement because there are some issues of how to meaningfully define 'gravitational energy'.
iKnightly
So energy is like the most basic....'thing'?
Most certainly not. That energy gets singled out for that sort of metaphysical finagling is actually a pet peeve of mine. Energy is just one conserved current due to time symmetry of a physical system; it's not like it's the only conservation law (heck, it's possible to design a system to have infinitely many conserved quantities). From the perspective of general relativity, energy is just one degree of freedom of spacetime curvature.