I haven't had much time to sew recently so I was pretty happy to string a few hours together last week to make this mini for our quilt guild's holiday swap. The quilts didn't have to be holiday-themed, and truthfully I think this could stay up all year, but I was feeling festive so here it is. All of the little trees were improv pieced. I grabbed a bunch of rectangular green scraps and some Kona snow and just went for it. If you would like to try this, here is a very small, kind of limited, photo tutorial. My quilt finished at just about 21'' square.
Cut your green pieces into rectangles and match each one up with a rectangle of your background fabric. Longer, skinnier background pieces will give you taller trees and shorter rectangles make fatter trees. Cut the background rectangle in half along the diagonal to yield two triangles. Arrange the triangles on the green fabric to get an idea of where they will be. Flip the first one over and sew it to the scrap right sides together. Trim the seam to 1/4'' and press towards the background fabric. Repeat with the other side. (Note: My method only works for a solid background as there is no wrong or right side. You could still do this with a print background, but you will need to more fabric to ensure that you have two triangles that point in opposite directions.
Trim the trees so that there is at least 1/4'' on each side of the bottom points and at the top. You can even out the height of the trees after the trunk is added by sewing extra background fabric to the top edge.
To make the trunks, sew a strip of brown fabric (7/8'' to 1 1/4'' wide by about 8" long) between two wider (about 3'' x 8") strips of background fabric. Press the seams towards the brown. Cut this into strips of different heights for trunks. For this quilt, I made two different strip sets and cut each into 6 pieces. Sew the trunks to the bottom edge of the trees and trim the sides.
Sew some strips of background fabric on each side and between the trees to act as spacers. I put four trees in each row and then sewed the rows together. You might want to add more background fabric along the top and bottom - I found it was nice to have some more negative space. Now make a quilt sandwich and quilt as desired - I went with unevenly spaced horizontal and vertical lines using my walking foot. Bind in your preferred method and admire your work.
I know the photos are limited, so if you have questions, please ask. I will answer in the comments for all to see.