Choose and prepare the flowers. Harvest flowers in the morning after dew dries or purchase your edible flowers from a safe source. Snip off stems and bulk green bases (calyxes). For larger flowers like roses, carefully remove petals.
Wash and dry the flowers. Gently wash the edible flowers then blot to dry on a paper towel. Let them air dry for 10-15 minutes until there's no moisture.
Build your "pressing sandwich." Fold a piece of parchment paper or wax paper in half and place it in the middle of a large book. Put a piece of printer paper on top of it. Place the flowers face down on the printer paper, making them as flat as possible and ensuring they don't touch. Put another piece of printer paper on top of the flowers. Be careful to make sure the flowers stay flat and don't fold over. Close the parchment paper over the top of the printer paper and close the book. Alternatively, you can place the printer paper directly on the counter or another flat surface, rather than inside of the book.
Add weight. Place another heavy book or two on top. You could also place a cutting board with weights or cast-iron skillet on top. Even, steady pressure is the goal.
Check for dryness. Let the flowers press for at least 1-2 hours. For the flattest blooms, it's best to wait 24-48 hours. The petals should feel dry at the edges with no cool or damp spots in the center. If your kitchen is extra humid, you might need to swap out the printer paper with fresh pieces to help wick moisture.
Use or store the flowers. Lift the flowers with tweezers to avoid damaging the bloom. If you're not using them immediately, place them between parchment paper in an airtight container. Add a small silica gel packet if you have one. Store the container in a cool, dark, dry spot away from heat sources. Use within 2-4 weeks for the best color.