Hello, PurplePepsiLady--
Might as well get used to it; the world is covered with trash like that. Once you find a fantastic diamond ring, you'll be hooked and easily convinced that the treasure is worth digging up some trash for.
Those rocks you're finding are referred to in these circles as 'hot rocks', they can contain very fine-grained magnetite or other minerals that make your detector sound off. If you have a ground balance adjustment, you should be able to tune them out. If you dig up a hot rock, follow the procedure in your manual to adjust your ground balance while using that rock as your target. After doing that, you shouldn't find them as frequently.
Hope this helps!