Here's more versions of the same that produce slightly different results:
glob.iglob()
import glob
for f in glob.iglob("/mydir/*/*.txt"): # generator, search immediate subdirectories
print f
glob.glob1()
print glob.glob1("/mydir", "*.tx?") # literal_directory, basename_pattern
fnmatch.filter()
import fnmatch, os
print fnmatch.filter(os.listdir("/mydir"), "*.tx?") # include dot-files