Journal of Discourses
These sets can be hard to find – you mostly have to get them on ebay, amazon, or second hand bookstores in Utah. Deseret says they sell them, but they are mostly ‘currently unavailable’. Prepare to spend a few hundred dollars (even $1000), even for a used set.
You can also find them online at http://scriptures.byu.edu/, among other places, but the nice thing about the Church’s site is there is a topical search, which is really necessary.
There is also a nice phone application called “Citation Index”, which has a topical search of the J of D, among other resources.
Be prepared to be challenged when you read through this set – you will find teachings here by our early Church leaders that you won’t find, or are even denied, in our Church today.