I have had an article published (with Pictures) in the Amateur Photographer in UK. It was some time ago and was dealing with film development so that will give you an idea. I did it on spec and it was accepted and I was subsequently paid.
Apart from being turned down, you have nothing to loose by sending images off together with a well written article to accompany them. Magazines have their own scale of charges so what you may get may differ. It may help if the images have never been published before and it goes without saying your script and images must be your copyright. It is easier now by E mail that it was when everything had to go by letter post.