I was hoping someone else would answer this for you because my description is so poor, but here goes:
Most Salvias have a fake thing at the base of the caylx that some people think you peel open to get the
seeds because it is black and looks like it should yield something useful. I'm not sure what it's called, and I'm not sure what they are, but they aren't
seeds. The fake
seed is sort of attached to the pod, and you have to pick it loose, whereas
seed is not attached as long as the
flowers have all turned brown.
The real
seed at the bottom of each husk (dried
flower pod), one-four per
flower. They are round, not flat, and usually oval in shape, and a chestnut brown to black, depending on the kind of Salvia. If you have a *dried* scape with many
flowers, you can sort of hold it horizontally and tap it against something and the
seed pods facing down will drop their
seed. Rotate it, and they keep dropping. You don't want to beat it like a crazy person or they'll come out and fly off the plate, just sort of tap it.
You will have a bunch of junk mixed in with the
seed, so just lightly blow and the chaff will blow off and you'll be left with the
seed which is relatively heavy.
There are many red salvias, and some will come back for you, and some are annuals which will not come back for you unless they self-sow.
I never throw away the chaff of Salvias because I always miss some
seeds...I just crumble it up and toss it out in
spring to see what might germinate.