Put a few flowers on blotting paper or some other absorbent paper or newspaper. Then put another piece of paper on top. Put heavy books on top and leave for a week. 
You could take a few crocuses, primroses or other flowers from your garden to press throughout the year. You can use them for cards, or calendars or even a lampshade. You can also mount them on transparent sticky back paper and use them as a window display.