I had a good old Tidy last week, and was surprised and not a little pleased to find my old flower press and some of its produce tucked away. The last time I moved house I went round the garden and took a sample of each plant as a memento. Some of them pressed better than others - white flowers always tend to go brown if they're too fleshy - but I was able to construct a couple of pictures to remind me of past glories. Last week I found the leaves I hadn't used yet, and reckon they could be kept for greetings cards etc.
I was lucky enough to be given a press, several layers of cardboard and blotting paper in a wooden frame with tightening screws. You don't need one though - just some slightly absorbent paper to go beneath and above the flowers, a heavy book and another heavy book to weigh it shut. Be careful how you lay the flowers, as they won't all open out beautifully once you close the pages over them. Get a few of each kind so that you can pick the best-turned-out for your project. It'll take a couple of weeks for them to dry out completely. To stick them to something, use a very very fine scraping of PVA glue on the surface and a DRY, SOFT paintbrush to ease the petals down flat. Lay them out in a plan before you get sticking, and try a few different arrangements.
You don't have to make big pieces as above - a single blossom on a small piece of card can be tucked into a clear plastic keyring-dongle. A silhouette portrait could be enlivened with flowers in the hair or as a border. Elderly female relatives will appreciate your efforts as cards, and even a plain picture can become more of an abstract collage than a reproduction of a garden. Don't forget that delicate leaves also work, especially variegated and feathery types.
Now that autumn months are drawing close, nab the last blooms of August while they last, and make them keep!