Hi Mistergee,
I live just outside of Philadelphia as well. I have been collecting for 18 years, and finding collecting sites remains difficult. This is particularly true since sites come and go - last year's productive field can be this year's housing development.
I would buy a detailed atlas of the area in which you wish to collect (for the Perkiomen Creek, I would buy a Franklin's Atlas for Montgomery County), and then I would go through it page by page, looking for areas near streams that also might have farms. Then I would go visit these areas, and if you see tilled fields, ask the farmer if artifacts occur on his land, and if so, request permission to collect at an appropriate time. Right now, with corn high on many fields, you might be asking for permission to collect next spring. It is worthwhile to do R&D trips with no expectation of collecting that day, but simply lining up possible sites for a future time.
You might also look for construction sites near water - sometimes these produce artifacts. Construction sites obviously come and go, and represent short-term collecting opportunties.
Never, ever, enter private land (including construction sites) without advance permission from the owner. Also, stay off federal or state land, including stream beds within such land. In particular, do not attempt to collect artifacts in Valley Forge National Park.
I believe that when a collector has permission, he has an implicit contract with the owner that he will take nothing but artifacts, and leave nothing but footprints. No other changes to the status quo. That means no leaving of trash, no boisterous behavior, no stepping on crops, and leaving gates open or closed, as you find them.
Network with collectors and friends, as others have said. I have been introduced to a couple of nice sites through business friends.
Be prepared to put in many hours seeking out sites, and then walking the fields. I find that even productive fields normally are sparse in quality artifacts. Moreover, some large fields may have the artifacts concentrated in small areas, with little to be found over most of the field.
When exploring a site, look for sharp, lithic flakes (reduction flakes) that were struck from the manufacture of artifacts. In southeastern Pennsylvania, look for flakes of quartz, quartzite, jasper, argillite, and various flints and cherts. Reduction flakes of quartz often look like shards of broken glass. Reduction flakes are noticeably different from rounded pebbles that one normally finds, so if you encounter reduction flakes, go over that area carefully.
Avoid "quartz blindness". Quartz is by far the most common material for artifacts on many southeastern Pennsylvania fields, and it is easy to focus on all the white lithic debitage and not be attuned to other lithics of different colors. If a nice jasper point is lurking in a field strewn with quartz, you would not want to miss it.
Finally, remember that there is a great deal of competition. Walking fields for artifacts is a very common hobby, although I suspect a number of people who do it pursue the hobby rather casually. Don't lose heart if you come to a field, and find it covered with footprints from another collector.
artorius
