Each winter I like to collect a bag or two of the seedheads of both Teasel and Greater Burdock in hope of rearing the three species of moth mentioned below.
On Teasel, I check seed heads for the larvae of Endothenia marginana and E. gentianaeana - studying the larvae closely allows me to separate the two: http://www.ukmoths.org.uk/show.php?bf=1099. This way I can be sure of an accurate ID of the adults. These larvae are often very numerous and not at all difficult to locate.
E. marginana - reared ex teasel seed head (larvae examined)
E. gentianaeana - reared ex teasel seed head (larvae examined)
I also always have a bag or two of Greater Burdock seedheads for rearing Metzneria lappella - I don't bother looking too closely, just harvest a few handfuls and then wait...
M. lappella reared ex burdock seed head