Dear Jim,
The envelopes are surely one of the valuable resources. The one you found says not only 'Barycz', but also 'Wesoła'. There is 10 places called 'Barycz' in Poland and ca. 11 called 'Wesoła'. The two nearest ones are in the former
Galicia and now in podkarpackie county, see:
http://maps.google.pl/maps?f=q&source=s_q&hl=pl&...The information itself is not very useful however, as you do not know the sender of that letter. But if you look at the distribution of the name Knurek in Poland:
http://www.moikrewni.pl/mapa/kompletny/knurek.html you will find that it is most popular in the Brzozów district - the same where Barycz is located in.
We can therefore with high probability state two things:
1. The letter was posted in Barycz/Wesoła, near Brzozów, podkarpackie county,
Galicia, during WWI,
2. Katarzyna Knurek came most probably either from Brzozów or from Wesoła.
You did not specify the question however and we don't know what we are looking for therefeore it is difficult to say how useful the information is. If you would like just to provide that information 'to whom it may concern' I would suggest you post it on the Poland/unknown board with the subject: 'Katarzyna Knurek from Barycz/Wesoła to
Springfield,
MA, 1914' and specifying the surname Knurek in the appropriate field.