The Obol denomination
The Obol was a form of ancient Greek currency and weight. Originally a small metal spit, six obols constituted a Drachm - a 'handful'.

Depending on the standard used, and obol weighed between 0.44 grams (Achaean) and 0,72 grams (Attic).
Obol

(1) Abdera 473-448 BC
Obverse: seated griffin left rising leg
Reverse: quadripartite incuse square
Ref: May 191; SNG Cop. 312 ff.
(2) Abydos (Troas) 480-450 BC
Obverse: eagle left, star above; ABY
Reverse: facing head of Medusa within incuse square
Ref: SNG Copenhagen 5; BMC 4-5
(3) Alexander III 325-300? BC
AR Obol Unknown mint
Obverse: Head of young Herakles right, wearing lion's skin
Reverse: Zeus seated left, leaning on scepter, holding eagle AΛEΞANΔPOY
Ref: None provided
(4) Aspendos c. 465-430 BC
Obverse: Amphora
Reverse: triskeles, pellet; E_Σ
Ref: SNG France 14; SNG von Aulock 4485;...
(5) Assos c. 479-450 BC
Obverse: gryffin right
Reverse: lion head right
Ref: BMC Troas p. 36, 3; Weber 5318; SGC...
(6) Evagoras I 411-373 BC
Obverse: Bare head of young male facing right (Evagoras?)
Reverse: Smooth, no design
Ref: BMC 45; Tziambazis 116
(7) Kebren c. 500-400 BC
Obverse: head of Apollo left
Reverse: ram head left within incuse square
Ref: SNG Ashmolean 1086 (diobol); SNGvA ...
(8) Kos 500-480 BC
Obverse: crab
Reverse: quadripartite incuse square
Ref: SNG Copenhagen 615-6 (diobols); HGC...
(9) Laranda Circa 324-323 BC
Obverse: Baaltars seated left holding long scepter, bunch of grapes and ear of grain
Reverse: Forepart of wolf right; inverted crescent above; all within circle of pellets.
Ref: Göktürk 82; SNG France 443
(10) Laranda c. 400-300 BC
Obverse: Baal seated left, stalk of grain and bunch of grapes in right hand, long scepter vertical behind in left hand
Reverse: wolf forepart right, crescent above
Ref: SNG BnF 450 (uncertain Cilicia), SN...
(11) Miletos 520-500 BC
Obverse: head of lion left
Reverse: star ornament within incuse square
Ref: Pfeiler, 6; SNG von Aulock 2080; BM...
(12) Miletos 520-500 BC
Obverse: head of lion left
Reverse: star ornament within incuse square
Ref: Grose 8210, SNGvA 2081, SNG Cop 944...
(13) Neandreia c. 410-370 BC
Obverse: laureate head of Apollo right
Reverse: ram right; NEA / N
Ref: SNG Cop 446; SNGvA 7628; SNG Munche...
(14) Pharkadon 480 - 400 BC
Obverse: Horse prancing right
Reverse: ΦΑΡ-ΚΑΔO, Athena standing right, holding spear and shield; all within incuse square.
Ref: BCD Thessaly I 1271 var. (ethnic), ...
(15) Selge 350-300 BC
Obverse: Facing gorgoneion
Reverse: Helmeted head of Athena right; astralagos behind
Ref: SNG France 1934
(16) Selge 250-190 BC
Obverse: Facing gorgoneion
Reverse: Helmeted head of Athena right within incuse square
Ref: SNG von Aulock 5242
(17) Selge c. 350-300 BC
Obverse: facing head of Medusa (Gorgoneion), tongue protruding
Reverse: head of Athena leftwearing crested helmet; astragalos behind
Ref: SNG BnF 1928; SNGvA 5281; BMC Lycia...
(18) Side c. 400-300 BC
Obverse: lion head right
Reverse: helmeted head of Athena right
Ref: Atlan, Side 77 (dies Exemplar); SNG...
(19) Tanagra 387-374 BC
Obverse: boeotian shield
Reverse: forepart of horse right; TA
Ref: BCD Boiotia 280; SNG Copenhagen 231