I decided to post this tutorial immediately since several people asked how I made those pressed flower trays for my mom.  This DIY is super easy and only requires a few things but has tremendous creativity potential!  

THINGS YOU WILL NEED:

1. pressed/dried flowers (see my notes below) OR pressed tissue flowers
2. mod podge
3. q tips
4. paper towels
5. paint brush 
6. rubbing alcohol
7. trays (I used these here, here & here)

NOTE:  allow at least 7 days for pressing/drying real flowers.  Also I would recommend using flowers that are NOT full (instead of gerber daisies/roses/carnations use something like orchids). You should be aware that the flowers may change color a little bit with the mod podge.  I would personally recommend using tissue flowers or even tissue sticker flowers (like this which can be found at Joann/Michael's craft stores) for this DIY.  

INSTRUCTIONS:

1. clean off your plates/trays with the rubbing alcohol.  let dry.
2. arrange your pressed flowers on your plates and take a pic on your phone when you have an arrangement you like.
3. using the brush, carefully brush a thin layer of mod podge on the back of you flower (if you  have a layered effect then start with the lowest layer first!)
4. place the flower on the plate and press down gently but thoroughly to get any air bubbles out.  continue with this process until all your flowers are stuck to your tray.
5. finally, brush another layer of mod podge on top of all your flowers on your tray.  be gentle!  otherwise you could tear a petal.  let this layer dry completely (~20 min) before putting on another layer.  use q-tips and paper towel to wipe excess mod podge.  let this dry completely.