That's a Charles III half real, definitely late 1700's! Looks like it's from the Mexico mint as think I see the 'oM' mint mark on the reverse. Very cool! This would have been just enough money to buy a large tankard of rum back then.
only took about 12 yrs to make the 1700s club!! still cloud 9.. never thought it would happen too me.. always thinking them guys down south and out east got it good..
and here i am in Cent IL were ur lucky to find mid or early 1800s coins ( 1831 William IIII the oldest to date ) so that goes to show it can happen at any time on any hole.
just have to get the coil on the soil and keep at it!! gold coin here i come, ur next!!