I have grown plants from seeds i got with weed many times and it works well. I enjoyed a lot of the buds I got from the plants. Like anything some is better than others and seeds from a really good bag of pot will equal better plants.

But like everyone else has said if you are really serious or want to be a pro, order seeds or clones. But giving it a try with seeds you already have is a good way to get started without spending a lot of money.