biggest coin should be something lke :
jeton van Georg Schultes
IORG+SCHULTES+
Book : Mitchiner, 1988: nos. 1309-1310
Book : L.Forrer Medalist, volume5
SCHULTES, GEORG (Germ.). Counter-Manufacturer at Nuremberg, circ. 1550.
Book : Neumann, Beschreibung der bekanntesten Kupfermunzen. Prag, 1868, V, p. 403, describes seven counters, some of which are dated 1551, 1552, 1553, and 1556, on which the Engraver's (can be found with google)
name occurs in the following forms : IORG SCHVLTES SPENGLER ZU NORMBERGIGMA; IORG SHVLTES SPNGLER ; IORG : SCHVLDDS : IORG; IORG SCHVILTES and GEORG. SCHVLTES. IN NVRBERC.
Georg was possibly the father of Hans Schultes, and the founder of the Schultes Counter-Manufactory.
here you find a picture :
brass, 24,5mm


here I have traced the tekst :


The other counter tokens should look very much the same
You find them in pure brass, but also silverplated.
For cleaning, I do not think they have any value to make it worthwhile.
Aceton or nailpolishremover may remove any grease. You also can try an light acid, but possible result may be worse