It's a Carlos IV (IIII) reales coin minted in Mexico City in 1796. Carlos IV reigned between 1788 and 1808 so the coin, if real, couldn't be dated 1726.
If it's a 4-reales, it will weigh 13.54 grams and be 34 mm in diameter. If an 8-reales, it would weight just over 27 grams and be 40 mm in diameter. If real, the coin would contain .896 fine silver.
The legends will read: CAROLUS IIII DEI GRATIA (YEAR)
The reverse legend will read: HISPAN ET IND REX M (4 or eight) R then the two letters for the assayers name (FM).
The edge of a real coin will be 'corded'
If it turns out to be a real 4-reales coin as I described above, you have a real winner (several years ago that coin was worth about $150 in VG). If it's an 8-reales coin, several years ago the coin was worth about $20 in VG condition.
Don........