Random notes and rhythms are actually pretty difficult to sightread, and not much use in the long run anyway. You'd be much better off trying to read actual music.
Pop songs off the shelf are probably too hard for you to read at present, and probably even above your playing abilities. They also often have some rhythmic difficulties, and pop is not always played strictly as it is written.
A good sightreader can generally read stuff (so that it sounds OK) that is ~2 grades below what they can play after serious practice.
After only a year of playing, that means it will still have to be pretty simple. In my day (don't ask) there used to be "easy piano" arrangements of pop songs. You should have a look for those - they'll be more in line with what you should be able to do at present. And, they'll give you plenty to practice your reading on, so that as your general playing improves, your sightreading keeps pace.