Maryland probably wanted to secede but was kept in by the US army sitting on it.
This is a popular Southern-apologist myth. There was no secessionist action of any kind in Maryland until after the bombardment of Fort Sumter and Lincoln's call for troops to put down rebellion. Troops coming to Washington had to pass through Maryland. One regiment was attacked while changing trains in Baltimore by pro-Southern rowdies, leading to a riot, and the pro-Southerners in control of the the city. A state senator issued a totally unauthorized call for the legislature to convene (and presumably vote on secession). Meanwhile, other Union troops went by steamship to Annapolis and thence to Washington, bypassing Baltimore and its mobs. Governor Hicks called a proper session of the legislature; since the capital, Annapolis, was occupied by Union troops, and Baltimore was in disorder, Hicks summoned the legislature to meet in Frederick, in western Maryland. The legislature met, voted
unanimously that it did not have the power to declare secession, and also voted 53-13 against calling a convention with such power. At this time, the nearest Union troops were about 60 km away, at the junction of the Baltimore-Washington railroad and the Annapolis branch line.
It should be acknowledged that later in 1861, Union troops occupied Baltimore, imposed martial law, and arrested hundreds of known or suspected secessionists, including some members of the legislature. Governor Hicks (by then a Senator) said later: "Arrests and arrests alone saved Maryland... I approved them then, I approve them now, and the only thing for which I condemn the Administration... is that they let some of these men out!"
So, while there is no evidence that "Maryland wanted to secede", it is true that the Union Army made absolutely certain that Maryland couldn't secede.