Red Poppy group on Flickr, mostly real flowers rather than designs or art/ crafts.
Frayed at the Edges makes a knit poppy.
Erssie Knits has a crochet poppy but the pattern is not available on the site.
Seawood has crochet poppies (flowers) with a big button in the middle.
Kittyboo Crochet has a nice poppy pattern:
A little poppy brooch, made by me, using Rowan Cashsoft yarn. Here is the (very rough and ready) pattern using UK terms:
Ch 6. SS into 1st stitch to form a ring.
24 dc into ring.
DC into each DC, increasing every other stitch to get 36 stitches.
1 ch [1 dc 1 tr 7dbltr 1 tr 1dc 1ss] 3 times with last ss into 1st ch.
Join the two pieces.
For the centre I really just made it up as I went along. It’s a bit hard to describe but I basically made lots of loops and tied them together (a bit like making a tassle) then cut off the tops and stitched into the centre of the poppy.