Today we think mostly in terms of making beer. However, it wasn't the only use for this plant. Wikipedia will give you a good description of the plant and it's many uses.
Below is a recipe for Hop Yeast that comes from The Appledore Cook Book ©1872 by Maria Parloa.
Pare and boil one dozen mealy potatoes (they will boil in thirty miuutes) ; as soon as you put the potatoes on to boil, put a handful of hops into another kettle with three quarts of cold water, cover and boil (watch it that it may not boil over). When the potatoes are boiled, drain and mash fine; then strain the hops through a fine sieve on the potatoes (be sure that the hops are boiling when they are strained on the potatoes), and stir well; then add one half a cup of sugar, one fourth of salt, and one pint of flour; mix this well and strain through a cullender; let it stand until it is milk-warm, then stir in one cup of go"od yeast, and set it to rise where it will be warm. It will rise in five hours if the yeast is good. You can tell when it is risen by the white foam, which will rise to the top. When risen, put it in a stone jug, and stop tight. It is a good plan to tie the cork down, as it sometimes flies out. Set in the ice chest or on the cellar bottom. Make one third this quantity in summer if your family be small.
• Hop Yeast, No. 2.
In the spring and the first of the summer, when potatoes are poor, it is better to make yeast without them. Boil one fourth of a cup of hops in one quart of water, and strain it upon half a pint of flour; stir this well, and add two spoonfuls of sugar and one of salt, then strain through a cullender, and let it become milk-warm, when add one cup of good yeast. You need just as much yeast for one third the quantity made without the potatoes, as you would for the whole made with potatoes. Rise and bottle the same as the preceding.