Just wondering, but why would your mother refuse to let you lift? As lazy as this world is becoming, any parent should encourage their kid to be into exercise and fitness.
Anyway, on to my answer, which is me assuming that you have access to "regular" back yard stuff...
Chin-ups on any bar that can support your weight and Bench dips on a chair. (Google "Bench Dip" if you don't know what that is)
You could do incline push-ups by simply putting your feet up on your bed while doing push-ups.
Tie a piece of rope through a cinder block and use that as a grip and curl those. You can really curl anything heavy that you can get a good grip on.
Some sort of heavy metal rod could be used to do skull crushers.
If you could get your hands on some 5 gallon buckets, you could fill them with sand, put the metal rod through the handles and do dead lifts with them.
You could do cleans and overhead presses with a bag of mulch.
There are also a ton of videos on YouTube about home made gym stuff. Good luck!