Plastic fasteners for holding bed sheets and linens in place; Systems and kits consisting of plastic fasteners for holding bed sheets and linens in place; Plastic fasteners for holding bed sheets and linens in place, namely, (a) a plastic bed sheet attaching corner bracket, (b) a plastic bed sheet attaching side bracket, (c) plastic bed sheet locking strips for attaching a bed sheet to a plastic bed sheet attaching corner bracket or a plastic bed sheet attaching side bracket, (d) a plastic fastener accessory capable of being attached to a plastic bed sheet attaching corner bracket or a plastic bed sheet attaching side bracket, (e) an inflatable bladder that is usable with and/or connectable to a plastic bed sheet attaching corner bracket for lifting/lowering a corner bracket and mattress; (f) an air hose suitable for use with an inflatable bladder; a plastic fastener accessory capable of being attached to a plastic bed sheet attaching corner bracket or a plastic bed sheet attaching side bracket, the plastic fastener accessory consisting of one or more features selected from: (i) a side table top surface, (ii) a ledge or rim extending along an upper surface, (iii) a hole extending through an upper surface, (iv) a clip or clamping member suitable for fastening an object (e.g., a book, a phone, a computer pad or tablet, etc.) to a surface of the accessory, (v) a clothes hanger for hanging one or more items of clothing, (vi) a towel rack for hanging one or more towels, (vii) a scented or scent-generating component to provide a scent in the area near the accessory, (viii) a cup-/glass-holding feature, (ix) a bedside holster (i.e., for a hand gun or long gun), (x) a bedside light/lamp, (xi) a fan, (xii) an articulated arm, (xiii) a bed railing , (xiv) a kickstand component, or any combinations thereof; a plastic fastener accessory capable of being attached to a plastic bed sheet attaching corner bracket or a plastic bed sheet attaching side bracket, the plastic fastener accessory consisting of one or more electronic components therein and/or thereon, the one or more electronic components consisting of one or more of (i) a phone charging outlet, (ii) a 120V outlet (e.g., a standard home outlet), (iii) a music-generating device (e.g., a music speaker and/or Bluetooth component), (iv) a television screen or computer screen, (v) a charging pad (i.e., induction charging), and/or (vi) a medical monitor (e.g., to monitor a patient, to display patient information, etc.); inflatable bladders, each inflatable bladder being usable with and/or connectable to a plastic bed sheet attaching corner bracket for lifting/lowering a corner bracket and mattress; an air hose suitable for use with an inflatable bladder