There are…a lot of definitions for crown, so I am picking the ones that are most common or especially relevant.

AS NOUN

I. An ornament for the head, and immediately derived senses. (also: Christian crown of thorns)

2. A wreath or circular ornament for the head symbolizing victory.

3. The sovereignty, authority, or dominion of which a royal crown is the symbol; the rule, position, or empire of a monarch.

5.  fig. Something which adorns or adds distinction like a crown; a chief or crowning ornament or achievement.

With capital initial:

a. The wearer of a royal crown; the monarch in his or her official character; the supreme governing power of a state under a monarchical constitution.

b.  Law (chiefly Brit.). The prosecution, considered as representing a reigning monarch in criminal proceedings.

7. The tonsure of a priest or monk (cf. corona n.1 5); (in later use also) the fringe or circle of hair surrounding some styles of tonsure. [I find this definition particularly interesting because the adjective tonsured/untonsured is used a couple times in Ulysses.]

8. A flower or cluster of flowers likened to a crown; esp. a verticil or whorl of flowers. In early use also: †the disc (disc n. 7a) of a flower of a plant of the family Asteraceae ( Compositae) (obs.). [Note that Asteraceae is almost certainly the family of the “yellow flower with flattened petals” Bloom receives in his correspondence from Martha. Also note that there are at least 6 other definitions relating crown to flowers or fruits or plants that didn’t seem as relevant to include. There are also innumerable wildflowers, trees, weeds, fungi, etc that have common names containing the word crown.]

11. Esp. in names of constellations: a group of stars likened to a crown; usu. with distinguishing word or phrase; spec. = Northern Crown

12. A circle or halo of light seen around the sun, the moon, a shadow, etc.; a corona

a. A group of people or objects in a ring or circle. Now somewhat rare.

b.  Math. A figure consisting of the area enclosed between a circle and a larger concentric circle; an annulus.

a. The top part of the skull; the top of the head.

20. The top part of a hat or other covering for the head.

a.  Anat. The part of a tooth (in early use spec. a molar) that appears above the gum and is covered by enamel.

32. Any of various coins, originally one bearing the imprint of a crown. b. A British or English coin (latterly silver) with a face value of five shillings or (now) 25 pence, now minted only for commemorative purposes. Hence: a monetary unit based on this, the sum of five shillings (now hist.).

 

AS VERB

a. To place a crown, coronet, etc., on the head of, as a symbol of newly acquired sovereignty or royal status; to invest with sovereignty or regal power by coronation. Also: to place a crown, etc., on or around (the head).

b. To establish in a position of power or influence. Obs.

a. To place a wreath, or garland, or other circular ornament on the head of, in token of victory or honour, or as a decoration; to adorn with the aureole of martyrdom, virginity, etc. 

4.  trans. With with. To provide with a top or topping of what is specified, usu. so as to add beauty or dignity.

a. To cover, surround, or occupy the head or summit of, as a crown does, usu. so as to add beauty or dignity.

b. To have a surface covered or dotted with (less commonly by) something beautiful, rich, or splendid.

a. To add the finishing touch to; to be the triumphant culmination of.

b. To honour with a successful consummation or issue; to bring (efforts, wishes, etc.) to a successful and happy conclusion.

8.  trans. Chiefly literary. To fill to overflowing, or until foam rises like a crown above the brim. Now rare.

a.  trans. (in pass.). Of a baby’s head during labour: (originally) †to be surrounded by the dilated cervix (obs.); (in later use) to be surrounded by the vulval opening, without receding during contractions.