Yes, they are unattractive compared to tooth-colored fillings. But they're not ugly, and they are normal for American society.
No, they're not poisoning you with mercury; mercury isn't dangerous until it's been ingested by marine microorganisms and converted to methylmercury, which travels up the food chain and becomes concentrated into the bodies of older top predator fish.
Silver fillings were placed with certain principals of engineering. To make the filling stay in place, there must be mechanical retention. The dentist had to carve the shape of a reverse keystone into the tooth to make the filling hold fast. That locked it into place once the filling hardened. That was a lot of tooth structure to remove, but it was the only way to make it stay. Modern filling materials don't need that, because it is a chemical bond that locks it to the tooth, not a physical retention.
So, if you remove a silver filling, you are left with a very large hole. That is a big can of worms. The tooth was stable, and now it's been opened up, risking a fracture down to the root, which means extraction, and replacing it with something far more expensive.
A good alternative is to remove only the top of the filling, cover it with an opaque composite, then make the top layer something more translucent. That will keep the interior of the tooth stable, hopefully, while improving its looks. But still, watch out. Silver fillings aren't easy to adhere to. If you have all kinds of money to burn, leave the silver filling as a build-up, and cover the whole tooth with a crown. That will at least keep it bound together.
Good luck, and be careful in there.