After pressing things from nature, I embed them in the process, and this is a typical result. I made these yesterday, top to bottom, L to R: plain lavender paper, weeds and seeds in white paper, baby's breath and weeds in light lavender paper, wild violets in white, rose petals and leaves in white, onion skins and weeds in white, and rosemary leaves with rye seeds in pink paper.
Finally, this blank note card (with the onion skins and weeds) is what I have done with most sheets of homemade paper. With blank envelopes it can be written on as is, or another sheet can be inserted for the writing, see last photo.
Tracing or vellum paper works well for adding a writing sheet (thanks to Kathyinozarks for that tip!).