I casually collect those, too. They need to be divided into two categories though.
The square or rectangle "postage paid" corners can come in unlimited varieties, as outside printers applied them to the envelopes themselves and there was no limit to the different types or styles that could have been used. Also, these corners contained no date so the period of usage is hard to pin down. Such examples are generally less desirable, even though some do collect them.
The other indicias are early examples of metered mail. There is an on-line catalog (a work still in progress, I believe) at this link that can be used as an identifier and/or value guide:
http://en.wikibooks.org/wiki/Intern...s_Of_AmericaUnfortunately, some stamp collectors take a negative view of these items, as they are not really stamps. Others, however, have realized that these are truly collectibles, especially some of the earlier ones. In any event, none are going to make a dent in your net worth, as their realistic "catalog" value only has bearing on what a collector may be willing to pay for an item that he or she may not have and in many cases, the group of collectors interested in such things are rather limited.
Nevertheless, don't let that discourage you from collecting them. They are a true piece of early postal history and do provide a nice sideline to collecting traditional postage stamps.
Posted 06/16/2011 6:05 pm
