This tutorial is a great scrap-buster and can be made from a variety of materials: any fabric, wool felt, recycled wool sweaters, even paper would do.  It requires only basic sewing skills (and could be handstitched, even glued, by a young child).
 The finished envelope is 4 x 5"
3/8" seam allowance.

Materials:
♥  Fabric scraps, 2 x 9.5 x 8" or sewn together to make a piece that size
♥  Straight pins
♥  Scissors
♥  Thread
♥  Sewing machine
♥  Chalk or fabric marking pencil
♥  Envelope template
♥  Scraps of felt or other embellishing materials
1) Gather your supplies.Print and cut out the envelope template (reduce or enlarge if you like).
Prepare your two main pieces~ if you do not have scraps 8.5 x 9" you can sew pieces together to make the required size.
It works very well if you attach pieces at the places you will fold the finished envelope (as in the middle one pictured below).

2) Cut out your envelope pieces (2) along the solid lines.. Do not cut the slit yet!

3) Using some scrap felt (or heavier fabric like denim) cut out two pieces to reinforce the portions of the envelope which will be the tab and slot for closing. Set aside.
4) Embellish the front of the envelope.
Start by chalking the front square to insure that you stay within the bounds.
 Then add your details with wool, fabric, markers, whatever you choose.
I have made a stamp (1") and label with wool felt for this example.
Use pinking shears or a zigzag stitch to create the edge effect for the stamp.

If using felt, set your stitches to short and narrow to best attach the small pieces.
I used a darning foot for creating the spirals on the heart (and the writing on the other examples).
5) Align the two envelope pieces, right sides together, adding on the reinforcement felt and pin together.
6) Sew the pieces together using a 3/8" allowance and leaving a 1" opening for turning (return your stitch length to normal if you have shortened it!).  I prefer to leave this opening along one of the short sections in the side folds.

7) Once you have sewn around, turn and check to make sure all of your seams are accurate and then trim neatly.

8)  Turn out and be sure to use a finger or other implement to push out all corner seams.
9)  Press the entire piece, carefully folding in the raw edges of the opening.
10)  Topstitch the entire perimeter (got fancy stitches? use 'em!), being sure to catch the opening in the seam.  If you like, you can also topstitch along the folding lines.

11) Chalk and cut the slit through all layers. Finish the raw edges as you prefer (buttonhole, zigzag) ~ my buttonhole function and I are on the outs, so pardon my rough edges!.
12) Fold up your envelope, press seams heavily with steam and you are done!
 ... now write a note to someone you love and send it!
Have fun! ♥♥
You are welcome to make these for any reason you like (including to sell). 
Copyright protects the text and photos of the tutorial. 
And credit to the author is always appreciated!
©Beneath the Rowan Tree/ Lori Campbell, 2011.

And if you enjoyed this tutorial, please share the love~ tweet, like it... send to a friend and be sure to leave a comment here with any links to your finished projects, we'd love to see them!