The first thing you should do is to pay the rent. The lien means
that you cannot sell the property without the proceeds going to the
landlord. In any case, since you still owe your mom the money for
the purchase, you can't sell the stuff anyways. Keep paying your
mom, and start paying the landlord what you owe. Keep copies of the
checks and good records.
Re: Who has 1st Lien? Everything depends on who has already
placed a lien against the 'item(s) of value'. If your mom didn't
register your 'promissary note' to repay her in the county
recorder's office and get first lien position against the item(s),
then the landlord may have filed a lien and taken first lien
position.
The landlord has legal right to file a lien against your
property for rent owed through contract, regardless if they are
placed in the first, second, or whatever lien position. The fact is
the item(s) had the lien(s) attached to them to limit your ability
to collect any proceeds from the sale of the item(s) before the
lien amount(s) are satisfied.