If you do a Google Image Search for "Elvis Presley", you will come up with a number of photos of him playing guitar.
The most common pictures show him playing what looks like a Martin of some sort clad in a peculiar corset-like cover. Others show J200's and a couple of interesting looking f-hole guitars.
There are a couple of early shots that show him playing a small-bodied guitar similar to a Gibson B25, but the one frame that shows the headstock has no makers' decal.
Personally, I have always thought that the idea that he played a Hagstrom was an urban myth, probably thought up by someone desperate to sell one!
Why should Presley have bought a guitar made by an obscure Scandinavian maker when he had all the US makers to go at?