The 50c Millennium looks like an Incuse and in fairly good condition, so I'd pop it into a 2x2 for protection. Worth considerably more than FV.
The round 1966 50c is 80% silver and has some nasty green gunk on it. Get some 100% Acetone from Bunnings, and soak the coin until the gunk is gone, do not rub the coin, pat it dry with a clean cloth or tissue, then put it in a 2x2.
They're pretty common, but still worth a bit of love & care.
The 2001 Volunteer Dollar is as indicated by Coaster a Rim Cud coin and IMO should also be in a 2x2.
I have 4 of these, one of which has 2 rim cuds on it, a similar one may be visible in coaster's video.
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