The collecting of every day plates with interesting designs goes back to when plates were first used. However designs on plates became a selling point for the tea / dinner plate manufacturers eg blue and white, of which there are many patterns, when competition became fiercely and they wanted a slice of this market. Many of the famous potteries also produced very ornate designs for their tableware, Mason's is a good example.
Some early collectable plates are now very valuable and "Delft" ware, going back to the 18th century, is a good example of this. Most potteries, like Royal Worcester and Spode, produced interesting designs, often hand painted by renn artists (not intended for everyday use, but purely decorative). Essentially the "Decorative" plate, originally hand painted, became more available with the advent of transfer printing and mass production techniques in the 19th century.
Naturally the earlier plates, especially hand painted are very valuable, and usually out of reach of the ordinary collector. However there are many plates which are affordable from the 19th to the 21st century and readily available. The real problem is to decide what to collect, whether it is a modern day plate from Danbury Mint or a commemorative plate from Victorian times. The range is massive and it is, as always with collecting, a personal choice.
Most of the potteries worldwide produced decorative plates and one must decide what to collect, Art Deco, Blue and White, Belleek, Chinese, Clarice Cliff, Derby, Dresden, Meissen or Worcester to name only a few, or to collect by theme, Cats , Dogs, Horses, Flowers, Fish, Places, Commemorative, Birds and so on.
Decorative plates can play the same function as a painting or a print and may be used as part of an overall decorative theme in one's home or office. In fact there is no reason why one can not mix the two to produce an interesting effect. Experiment with a layout on the floor to start with, before committing to actually fixing them to the wall, it will save a lot of extra work filling in holes!
Since WWII the plate manufacturers like Royal Doulton, Wedgwood, Knowles, Danbury Mint, WSGeorge and many more have produced plates for this market and their plates are purely decorative and not functional, in fact they state that the paints used my be toxic. It goes without saying these plates are not dish washer safe. There are exceptions but they do not concern us here.
I believe the best approach is to study the various web sites and on line auction houses to see what interests you and then to concentrate on a particular area. We sort all our plates by theme which makes it easy to find a plate to complete a set or to replace a broken or lost one. Most potteries produce sets of plates, usually on a theme and are issued on a regular basis so you can acquire a complete set if you wish. This of course only applies to new editions. To find previous issues you need to hunt for them on web sites like ours. Many companies operate a finder service, as we do, but it may take a time to find that illusive plate.
Overall the collecting of decorative plates can be informative, pleasing to the eye or just plain fun. Good luck!