There are several glues you can use for flowers but there are two in particular that are very good. I actually sell both on my website: http://www.orchidaepressedflowers.com. And I use them exclusively in my pressed flower art.

The first is called Botanical Glue and it's great because it has a UV protectant in it and the consitencey is great to work with - a bit thicker than Elmers. It has a fiarly fast drying time.

The second is called PPA or Perfect Paper Adhesive. I recommend the matte version as the glossy version makes the end product look fake. It has a consisency a little thinner than Elmers so it gives you a littel more drying time to play around and move your flowers. It also has the UV protectant quality.

Hope that helps and just email me if you need any help.
Denyse
denyse@orchidaepressedflowers.com