Yes, RFID tags can be blocked from receiving signals by using metals like iron. Usually, an alloy called Mu-Metal is made up of nickel, iron, copper, chromium, and molybdenum is used for blocking RFID signals.
Also, a simple solution to protect your wallets from RFID signals is wrapping them in aluminium foils. The following characteristics of metals enable RFID signal blocking:
High permeability
Ductile and malleable
Resistant to corrosion and rusting
Light in weight
Non- toxic nature
Not overly reactive
Cheap availability
Also, metal RFID tags are available in the market.