You can eat all the stems or weed you want, it aint gonna make you high. You must extract the THC out of the weed in order to get high, thats why we smoke it! THC is ineffective without heating it to a certain point.
BUT, dont throw away your stems, they do tend to have a small amount of THC, use them when you make BUDDER or when you make brownies, u can extract the THC out of the Stems (or weed of course) easily by simmering them in hot oil, then drain and add to your brownie mix. When I make brownies I add about a 1/2 of Stems and about a 1/4 of weed. Perfect High!