Can I connect two extention cords together?

Purely for cosmetic purposes. I only use it for two 3w lamps and my iPhone/ iPad/ macbook charger (one or the other, never all at once). Could I have the two lights in one extension so that it can be hidden behind my bed with another extension coming off of it to plug my phone in to?

That's fine. But don't try to use anything requiring a higher power like a heater.

Sure, people do it all the time. Something like 50W is not a problem.

There are regulations around extension cords, and there are safety issues if they are not used properly. One issue is heat - if you run 1000W down an extension cord without unwinding it, or it's in a pile under a cushion and can't dissipate heat, the insulation can melt. Another is related - if the cord gets a lot of physical abuse and the connectors get loose, and then you run 1000W down it, the connectors can get hot or maybe arc and start a fire. And you aren't supposed to hide connections inside walls, or use extension cords instead of a properly installed permanent outlet. So if you were a commercial business, the inspectors would complain. But for someone at home to use a cord for a low wattage load, there's no problem unless your pet rabbit chews the insulation off.