…you’re my only hope.
I don’t know where to go about finding out what these plants are called. Do you know where I should look?
What kind of plant is this?
What tree is this?
What plant is this?
I probably shouldn’t eat this, right?
Help me, botanists
Between the Devil and the Deep Blue Sea 
So #3 is probably Genista monspessulana AKA French broom, and #2 is most likely Cercis siliquastrum AKA Judas tree, which takes its name from the κερκις, or weaver’s shuttle, to which Theophrastus likened it in his Enquiry into Plants.
And #1 may be Lamium album AKA white deadnettle, also known as the bee nettle. Or it may not.
I concur with your identification of #1 as a Lamium, and #2 as a Cercis. I had no idea Cercis as a genus was so widespread! Not sure of the other two, though #4 is really pretty.
I have been educated about Plants by Sarah Goslee on Twitter.