If you are Craft-oriented, making Seed Packets may be as enjoyable as Seed Collecting. Plus it will keep junk mail out of the landfills. Packets can be made from Junk Mail with a few simple cuts. Many envelopes have windows; select those that have 4" of non-window Face as shown above. Draw 2 lines across the Face of the envelope; one at the 4" mark, and one at the 5" mark.

Cut the Envelope in 'half' at the 5" mark. Then remove the area of the Face Only, between the two marks with a scissors. It may be easier if you slit the sides with a knife and then cut across the 4" Face mark with a scissors. Optionally, you may want to taper the flap as shown. Fold the flap over the Face and crease it.
This creates a 4" X 4" Seed Packet with a 1" closing flap.

Label the Packet with Variety, Date collected, Annual/Perennial/Biennial, Color, Size, etc. Insert your Dried Seeds and seal it with tape, glue, or staples. Store them with Silica Gel in an air-tight container.