If some one gave me upper and lower dentures, would they (the dentures) be able to be adapted to my mouth?

No. They have to take a mold of your mouth BEFORE they make the dentures. Once made, they can only be slightly adjusted--only to reline them or replace a broken plate. If they aren't made for your mouth, they can't do anything about that. Don't you think you'd look BAD wearing teeth that are either too big or too small for your mouth? Of course you would. If you need dentures, go to a local university website and see if they have a college of dentistry. You can go there for MUCH less.