I was looking at on-line stuff and found this. If you let your imagination run wild you can find lots of analogies but they do go back to similar sounding words and plugs and plows have similar shape (albeit in much different sizes). The final velar, however, separates them out
plow (n.) 
O.E. plog, ploh "plow, plowland (a measure of land)," possibly from Scand. (cf. O.N. plogr "plow"), from P.Gmc. *plogo- (cf. O.Fris.ploch, M.L.G. ploch, M.Du. ploech, O.H.G. pfluog). O.C.S. plugu, Lith. plugas "plow" are Germanic loan-words, as is probably L.plovus, plovum "plow," a word said by Pliny to be of Rhaetian origin. Replaced O.E. sulh, cognate with L. sulcus "furrow." As a name for the Big Dipper, it is recorded from 1513. The verb is first recorded c.1420. Plowshare is first recorded c.1380.
pluck (v.) late O.E. ploccian "pull off, cull," from W.Gmc. *plokken (cf. M.L.G. plucken, M.Du. plocken, Flem. plokken), perhaps from V.L.*piluccare (cf. O.Fr. peluchier, c.1180), a frequentative, ultimately from L. pilare "pull out hair,"
from pilus "hair." But despite the similarities, OED finds difficulties with this and cites gaps in historical evidence. Noun sense of "courage, boldness" (1785) is originally boxing slang, from meaning "heart, viscera" (1611) as that which is "plucked" from slaughtered livestock. Perhaps infl. by fig. use in pluck up (one's courage, etc.), attested from c.1300. Hence, plucky (1842). "To pluck a rose, an expression said to be used by women for going to the necessary house, which in the country usually stands in the garden." [F. Grose, "Classical Dictionary of the Vulgar Tongue," 1785]
This euphemistic use is attested from 1613.
plug 1627, originally a seamen's term, probably from Du. plug, from M.Du. plugge "bung, stopper," related to Norw. plugg, Dan. pløg,M.L.G. pluck, Ger. pflock, ultimate origin uncertain. Sense of "wad or stick of tobacco" is attested from 1728. Electrical sense is from 1883; meaning "sparking device in an internal combustion engine" is from 1886. The verb meaning "to close tightly (a hole), to fill" is first recorded 1630. Meaning "advertisement" first recorded 1902, perhaps from verb sense "work energetically at" (c.1865). The noun sense of "advertisement" is
from 1902, Amer.Eng. The verb meaning "to popularize by repetition" is from 1906. Slang verb sense "to put a bullet into" is recorded from 1870. Plug-ugly "ruffian" is first attested 1856, originally in Baltimore, fromplug, Amer.Eng. slang for the stovepipe hats then popular among young men.